Method for manufacturing nanoparticles

Abstract

[Problem] To provide a method for producing nanoparticles that is designed to improve nanoparticle production efficiency. [Solution] A method for producing nanoparticles according to one embodiment of the present invention comprises a formation process for radiating a femtosecond pulse laser on a substrate solvent comprising a precursor and forming nanoparticles, wherein the formation process is characterized in comprising: a radiation step for radiating the femtosecond pulse laser on the substrate solvent; an acquisition step for acquiring color information for the substrate solvent radiated by the femtosecond pulse laser; and a setting step for setting the radiation conditions for the femtosecond pulse laser on the basis of the color information.

Description

Technical Field

[0001] The present invention relates to a method for producing nanoparticles.

Background Art

[0002] Nanoparticles (hereinafter also referred to as NP (Nano Particle)) indicate a structure on the order of nanometers generated using existing materials, and are expected for various applications.

[0003] Patent Document 1 discloses a technique for controlling the particle size of nanoparticles by controlling the fluence (light intensity) of a laser.

[0004] Patent Document 2 discloses a technique for controlling the particle diameter of gold nanoparticles by changing the scanning speed of a laser.

[0005] Research and development has been carried out by the present applicant to put into practical use the use of NPs in a thermoelectric conversion element that does not require a large temperature difference, as proposed in Patent Document 3.

[0006] Also, the present applicant has disclosed a method for producing NPs using a femtosecond pulsed laser, as proposed in Patent Document 4. In this method, by limiting the diameter of the nanoparticles with the length of the molecular chain of the dispersant as a variable, it is possible to produce high-performance alloy NPs.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

[0008] By the way, in order to apply NPs to commercially available products, it is necessary to manufacture them more efficiently.

[0009] In this regard, the technologies disclosed in Patent Documents 1 and 2 do not consider the production of NPs in a solvent.

[0010] In the technologies disclosed in Patent Documents 3 and 4, a femtosecond pulsed laser is irradiated onto a solvent containing dissolved metal ions, but the irradiation conditions for efficiently producing NPs have not been investigated.

[0011] Therefore, the present invention was devised in view of the above-mentioned problems, and its objective is to provide a method for producing nanoparticles that improves the production efficiency of nanoparticles. [Means for solving the problem]

[0012] A method for producing nanoparticles according to the first invention comprises a production step of irradiating a basic solvent containing a precursor with a femtosecond pulse laser to produce nanoparticles, wherein the production step comprises an irradiation step of irradiating the basic solvent with the femtosecond pulse laser, an acquisition step of acquiring color information of the basic solvent irradiated with the femtosecond pulse laser, and a setting step of setting the irradiation conditions of the femtosecond pulse laser based on the color information.

[0013] The method for producing nanoparticles according to the second invention is characterized in that, in the first invention, the setting step sets the irradiation conditions based on the change in the color information of the basic solvent.

[0014] The third invention relates to a method for producing nanoparticles, characterized in that, in the first or second invention, the setting step includes setting the irradiation conditions, including the light intensity conditions of the femtosecond pulse laser.

[0015] The method for producing nanoparticles according to the fourth invention is characterized in that, in the first or second invention, the setting step includes setting the irradiation conditions, which include scanning conditions for scanning the femtosecond pulse laser.

[0016] The fifth invention relates to a method for producing nanoparticles, characterized in that, in the first or second invention, the setting step includes setting the irradiation conditions, which include focusing conditions that concentrate the femtosecond pulse laser with a focusing lens and convert it into a soft-focus beam near the focusing position.

[0017] The method for producing nanoparticles according to the sixth invention is characterized in that, in the first or second invention, the setting step includes setting the irradiation conditions, which include stirring conditions for stirring the basic solvent.

[0018] The method for producing nanoparticles according to the seventh invention is characterized in that, in the first invention, it further comprises an evaluation step for evaluating the state of existence of the material contained in the nanoparticles.

[0019] The method for producing nanoparticles according to the eighth invention is characterized in that, in the seventh invention, the evaluation step includes an observation step of observing the nanoparticles and acquiring a particle image; a detection step of acquiring a detection result showing the relationship between the detection intensity of a plurality of materials included in the particle image and the detection position; and a comparison step of comparing the relationship between the detection intensity and the detection position for each of the plurality of materials based on the detection result.

[0020] The method for producing nanoparticles according to the ninth invention is characterized in that, in the eighth invention, the observation step is performed by acquiring the particle image using a scanning transmission electron microscope.

[0021] The method for producing nanoparticles according to the tenth invention is characterized in that, in the eighth invention, the detection step obtains an approximate result as the detection result by performing an approximation method on the relationship between the detection intensity and the detection position.

[0022] The method for manufacturing nanoparticles according to the 11th invention is characterized in that, in the 10th invention, in the comparison step, the detection positions associated with the maximum values of the detection intensities in the approximation results are compared for each of the plurality of materials.

[0023] The method for manufacturing nanoparticles according to the 12th invention is characterized in that, in the 8th invention, in the comparison step, the spatial frequencies based on the detection results are compared for each of the plurality of materials.

[0024] The method for manufacturing nanoparticles according to the 13th invention is characterized in that, in the 8th invention, the evaluation step includes a measurement step of measuring the content rate for each of the plurality of materials using an X-ray diffraction method, and an accuracy verification step of evaluating the accuracy of the comparison result in the comparison step based on the measurement result in the measurement step.

Advantages of the Invention

[0025] According to the 1st to 13th inventions, in the setting step, the irradiation conditions of the femtosecond pulse laser are set based on the color information. That is, by using the color information of the basic solvent as an index indicating the generation state of the nanoparticles, it is possible to easily set and change the irradiation conditions suitable for the manufacture of nanoparticles. Thereby, it becomes possible to improve the manufacturing efficiency of the nanoparticles.

[0026] In particular, according to the 2nd invention, in the setting step, the irradiation conditions are set based on the change in the color information of the basic solvent. Therefore, the accuracy when setting the irradiation conditions can be improved. Thereby, it becomes possible to further improve the manufacturing efficiency of the nanoparticles.

[0027] In particular, according to the 3rd invention, in the setting step, the irradiation conditions including the light intensity conditions of the femtosecond pulse laser are set. Therefore, the control of the femtosecond pulse laser irradiated to the basic solvent becomes easy. Thereby, it becomes possible to further improve the manufacturing efficiency of the nanoparticles.

[0028] In particular, according to the fourth invention, the setting step sets irradiation conditions, including scanning conditions. That is, the irradiation area of ​​the femtosecond pulse laser can be changed in conjunction with the setting of scanning conditions. For example, if nanoparticles are produced without changing the irradiation area, then multiple metal ions and other precursors will not be present in that area (because the precursors have been converted into nanoparticles). Therefore, by changing the irradiation area and irradiating the area where precursors exist, the amount of multiple metal ions and other precursors present in the irradiation area of ​​the femtosecond pulse laser can be considered to be a constant value. As a result, it becomes possible to further improve the production efficiency of nanoparticles.

[0029] In particular, according to the fifth invention, the setting step sets the irradiation conditions, including the focusing conditions. That is, the femtosecond pulsed laser is soft-focused in conjunction with the setting of the scanning conditions. Unlike the light that spreads according to the numerical aperture value of the focus, the light spread, known as soft focus, is converted so that it does not spread regardless of the numerical aperture, thus making it possible to homogenize the light intensity near the focusing position of the femtosecond pulsed laser. As a result, the femtosecond pulsed laser is irradiated evenly onto the basic solvent, making it possible to further improve the manufacturing efficiency of nanoparticles.

[0030] In particular, according to the sixth invention, the setting step involves setting irradiation conditions, including stirring conditions. That is, as the basic solvent is stirred in conjunction with the setting of stirring conditions, gases such as oxygen and hydrogen generated in the light irradiation area are swept away, and precursors such as multiple metal ions can be efficiently supplied to the irradiation area. This makes it possible to further improve the production efficiency of nanoparticles.

[0031] In particular, according to the eighth invention, the comparison step compares the relationship between the detection intensity and the detection position for each of several materials based on the detection results. This makes it possible to quantitatively evaluate the degree of solid solubility of each material contained in the nanoparticles. This makes it possible to clearly determine the quality of the nanoparticles.

[0032] In particular, according to the ninth invention, the observation step involves acquiring particle images using a scanning transmission electron microscope. Therefore, compared to other methods for acquiring particle images, the degree of solid solubility for each material can be obtained with high accuracy. This makes it possible to evaluate the degree of solid solubility with high accuracy.

[0033] In particular, according to the tenth invention, the detection step obtains an approximate result as the detection result by performing an approximation method on the relationship between the detection intensity and the detection position. Therefore, even when the shape of the nanoparticles differs from a perfect sphere to a sub-nanometer value in the profile signal of the particle image, a decrease in comparison accuracy can be suppressed. This makes it possible to achieve stable evaluation of the degree of solid solubility.

[0034] In particular, according to the 11th invention, the comparison step compares the detection position associated with the maximum detection intensity in the approximate results for each of the multiple materials. Therefore, it is possible to easily evaluate the differences in the bias of the degree of solid solubility for each material contained in the nanoparticles. This makes it possible to easily evaluate the degree of solid solubility.

[0035] In particular, according to the 12th invention, the comparison step compares the spatial frequencies based on the detection results for each of several materials. Therefore, the differences in the content of each material contained in the nanoparticles can be easily evaluated. This makes it possible to evaluate the degree of solid solubility taking into account the content.

[0036] In particular, according to the 13th invention, the accuracy verification step evaluates the accuracy of the comparison results in the comparison step based on the measurement results in the measurement step. That is, the accuracy of the comparison results, which compare the state of existence of each material contained in a part of the nanoparticles, is evaluated using the measurement results that show the content rate of each material contained in the entire nanoparticle. Therefore, it is possible to evaluate whether or not the comparison results are valid as characteristics of the entire nanoparticle. This makes it possible to efficiently evaluate the degree of solid solubility of the nanoparticles. [Brief explanation of the drawing]

[0037] [Figure 1]Figure 1 illustrates an example of the relationship between the light intensity of a femtosecond pulsed laser and the manufacturing efficiency of nanoparticles. [Figure 2] Figure 2 is a diagram illustrating the self-focusing of laser light due to the optical Kerr effect. [Figure 3] Figure 3 is a schematic diagram showing an example of a nanoparticle manufacturing system according to the first embodiment. [Figure 4] Figure 4 is a schematic diagram showing an example of an irradiation apparatus in the nanoparticle manufacturing system according to the first embodiment. [Figure 5] Figure 5 is a schematic diagram showing an example of a control apparatus for a nanoparticle manufacturing system according to the first embodiment. [Figure 6] Figure 6 is a flowchart showing an example of a method for producing nanoparticles according to the first embodiment. [Figure 7] Figure 7(a) shows an example of the focusing position when a femtosecond pulsed laser is irradiated, and Figure 7(b) shows the change in the focusing position when the focusing lens is rotated from Figure 7(a) and the femtosecond pulsed laser is irradiated. [Figure 8] Figure 8(a) shows the arrangement relationship between the lens central axis and the rotation central axis from the direction of the rotation central axis of the focusing lens, and Figure 8(b) shows the basic solvent scanned by the femtosecond pulse laser in a circular orbit. [Figure 9] Figure 9 illustrates an example of the relationship between the light intensity of a femtosecond pulsed laser and the irradiation time required to produce a specific color. [Figure 10] Figures 10(a) and 10(b) are schematic diagrams showing an example of nanoparticles. [Figure 11] Figure 11 is a flowchart showing an example of the evaluation process. [Figure 12] Figure 12 is a microscopic image showing an example of a particle image. [Figure 13] Figures 13(a) and 13(b) are schematic diagrams showing an example of detection results based on two-dimensional directions. [Figure 14]Figures 14(a) and 14(b) are schematic diagrams showing an example of detection results based on one dimension, while Figures 14(c) and 14(d) are schematic diagrams showing the relationship between detection results based on two dimensions and detection results based on one dimension. [Figure 15] Figures 15(a) and 15(b) are schematic diagrams illustrating an example of the approximation results. [Figure 16] Figures 16(a) and 16(b) are schematic diagrams showing an example of the degree of deviation. [Figure 17] Figure 17 is a schematic diagram showing an example of a nanoparticle manufacturing system according to the second embodiment. [Figure 18] Figure 18 is a schematic diagram showing an example of a nanoparticle manufacturing system according to the third embodiment. [Figure 19] Figure 19 is a schematic diagram showing an example of a nanoparticle manufacturing system according to the fourth embodiment. [Modes for carrying out the invention]

[0038] Hereinafter, an example of a method for producing nanoparticles as an embodiment of the present invention will be described with reference to the drawings.

[0039] (First Embodiment) The nanoparticle manufacturing method in this embodiment involves irradiating a basic solvent containing a precursor with a femtosecond pulsed laser to generate nanoparticles containing metal atoms, etc. In the nanoparticle manufacturing method, the irradiation conditions of the femtosecond pulsed laser can be set based on color information described later. For this reason, for example, irradiation conditions can be easily set to change from a "high light intensity region" where the nanoparticle manufacturing efficiency is extremely low relative to the light intensity to a "low light intensity region" where the nanoparticle manufacturing efficiency is good relative to the light intensity. Furthermore, for example, by evaluating the degree to which nanoparticles have been generated using color information, it is possible to set irradiation conditions that show the optimal manufacturing efficiency even within the "low light intensity region," as well as the timing for ending the generation of nanoparticles.

[0040] The precursor used in the nanoparticle manufacturing method includes, for example, one or more types of solid particles. The solid particles include, for example, multiple particles having a finite particle diameter of 500 μm or less. The solid particles have a median diameter larger than the median diameter of the resulting nanoparticles. The solid particles have a median diameter of, for example, 50 nm to about 100 μm.

[0041] The material of the solid particles refers to the material contained in the nanoparticles, and for example, refers to atoms such as metal atoms. The precursor may include, for example, two or more types of solid particles, each containing a different material.

[0042] In addition to the above, the precursor may include, for example, an organometallic complex. In this case, a material having a phenyl group may be used as the basic solvent. Examples of organometallic complexes include alkyl complexes such as CH3Li (methyllithium) and CH3CH2MgBr (ethyl Grignard), aromatic complexes such as Fe(C5H5)2 (ferrocene), and acetylacetone complexes such as Cu(C5H7O2)2 (copper acetylacetonate), as well as other known materials.

[0043] In addition to the above, the precursor may contain one or more metal salts. The metal salt contains known compounds containing metal ions, and any material can be included depending on the application. The metal salt contains one or more materials. For example, if the metal salt contains two or more materials, nanoparticles containing each material can be produced. As the metal salt, known metal salts such as HAuCl4·3H2O and H2PtCl6·6H2O can be used.

[0044] In the following explanation, metal ions are used as an example of a precursor. However, since the same manufacturing method is shown for metal salts, solid particles, etc., as precursors, the explanation will be omitted.

[0045] For example, as shown in Figure 1, the characteristics of nanoparticle manufacturing efficiency can sometimes be classified into four regions based on the light intensity per unit area of ​​a femtosecond pulsed laser. In this case, the aforementioned "low light intensity region" corresponds to regions 1 to 3, and the "high light intensity region" corresponds to region 4.

[0046] When a femtosecond pulsed laser with a light intensity within the first region is irradiated onto a basic solvent containing dissolved metal ions, reduction is unlikely to occur, resulting in low nanoparticle production efficiency. When a femtosecond pulsed laser with a light intensity greater than the first region (within the second region) is irradiated onto the basic solvent, reduction occurs, increasing nanoparticle production efficiency. When a femtosecond pulsed laser with a light intensity greater than the second region (within the third region) is irradiated onto the basic solvent, the reduction saturates, and the nanoparticle production efficiency also saturates. On the other hand, when a femtosecond pulsed laser with a light intensity greater than the third region (within the fourth region) is irradiated onto the basic solvent, the nanoparticle production efficiency becomes lower than the saturated nanoparticle production efficiency.

[0047] Thus, we found that the nanoparticle manufacturing efficiency increases in the low light intensity region, which corresponds to the first to third regions, where the light intensity of the femtosecond pulse laser irradiating the basic solvent is below a predetermined value, while it decreases in the high light intensity region, which corresponds to the fourth region, where the light intensity exceeds a predetermined value. This is thought to be due to the optical Kerr effect, in which the birefringence of a substance changes in proportion to the square of the electric field strength when the substance is irradiated with an electric field in the form of light.

[0048] As shown in Figure 2, the optical Kerr effect causes a self-focusing phenomenon in which the laser beam repeatedly converges as if there were a convex lens (Kerr lens). Because the laser beam has self-focused, it can only illuminate a spatially limited area, making it difficult to supply metal ions to areas not illuminated by the laser beam. Therefore, it is thought that the efficiency of nanoparticle manufacturing decreases.

[0049] Therefore, the inventors have shown that the phenomenon of self-phase modulation generated by the optical Kerr effect can be utilized. By irradiating with short-duration pulsed light, such as a femtosecond pulsed laser, a nonlinear refractive index effect occurs, where the refractive index differs between the peak and tail portions of the pulsed light intensity, resulting in different phase advances. A phase change proportional to the intensity of the pulsed light occurs, and the time derivative of the phase is the frequency. Since frequency corresponds to wavelength, the wavelength changes due to self-phase modulation. In fact, when a femtosecond pulsed laser near 800 nm is irradiated onto a basic solvent, light that has spread (chirpened) from 400 nm to 700 nm due to self-phase modulation is observed as white light. At this time, the light intensity falls within the "high light intensity region," which reduces the nanoparticle manufacturing efficiency. Therefore, by controlling the irradiation light of the femtosecond pulsed laser so that the observed light does not become white light, the light intensity can be changed to within the "low light intensity region," thereby avoiding a decrease in nanoparticle manufacturing efficiency. Therefore, in the nanoparticle manufacturing method, it is possible to improve the nanoparticle manufacturing efficiency by acquiring "color information" for the irradiated area when a femtosecond pulsed laser having the above-described optical characteristics is irradiated onto a basic solvent, and by setting the irradiation conditions.

[0050] Furthermore, the inventors have discovered that the phenomenon of localized surface plasmon resonance (hereinafter also referred to as LSPR (Localized Surface Plasmon Resonance)) can also be used to control the irradiation light, for example. In LSPR, when light is incident on a basic solvent in which metal ions that will become components of nanoparticles are dissolved, the free carriers (electrons or holes) in the nanoparticles resonate with the wavelength of the incident light and collectively vibrate, causing a phenomenon in which they resonate at a specific wavelength. When observing the light that transmits and illuminates the basic solvent, a specific wavelength is absorbed due to resonance, and the absorption wavelength band is attenuated from the wavelength band at the time of incidence of the illumination light, resulting in a different wavelength band, which is what is known as "coloring." Therefore, in a nanoparticle manufacturing method, when a femtosecond pulse laser is irradiated onto a basic solvent having the above-described characteristics, it is possible to improve the efficiency of nanoparticle manufacturing by acquiring "color information" related to the color change of the basic solvent associated with the generation of nanoparticles and setting the irradiation conditions. In the nanoparticle manufacturing method, the irradiation conditions can be set based on at least one of the two types of color information described above.

[0051] In the method for manufacturing nanoparticles, for example, a nanoparticle manufacturing system 100 may be used. The nanoparticle manufacturing system 100 uses the color information of a basic solvent to set the irradiation conditions of a femtosecond pulsed laser and manufactures nanoparticles. In the nanoparticle manufacturing system 100, for example, by controlling the irradiation light of the femtosecond pulsed laser so that it does not become white light, nanoparticles can be manufactured efficiently.

[0052] As shown in Figure 3, the nanoparticle manufacturing system 100 comprises a container 2, an irradiation device 3, a color information acquisition device 4, and a control device 1.

[0053] As shown in Figure 4, the container 2 contains a basic solvent 6 containing a precursor, which is a basic solvent 6 in which metal ions such as gold ions or platinum ions are dissolved in the solvent. The solvent can be a liquid such as water or an organic solvent. The container 2 is, for example, a cuvette made of quartz glass. A stirring bar 21 is provided inside the container 2, and the basic solvent 6 contained therein can be stirred by the stirring bar 21. The basic solvent 6 contained in the container 2 is stirred according to the stirring conditions set by the control device 1. Note that the state in which the precursor is contained in the basic solvent 6 may refer to a state in which metal ions are dissolved in the solvent, or a state in which solid particles or metal salts are dispersed in the solvent.

[0054] The irradiation device 3 is for irradiating the basic solvent 6 contained in the container 2 with a femtosecond pulsed laser. The irradiation device 3 irradiates with a femtosecond pulsed laser in a parallel beam. The irradiation device 3 irradiates with the femtosecond pulsed laser based on the irradiation conditions set by the control device 1. The irradiation device 3 is equipped with a focusing lens 31.

[0055] The focusing lens 31 is, for example, an aspherical lens. The focusing lens 31 is equipped with a hollow rotary actuator (not shown) and is configured to rotate around a rotational axis C1 along the irradiation direction of the femtosecond pulse laser. The lens central axis L1 of the focusing lens 31 is positioned eccentrically by an eccentricity amount E from the rotational axis C1. The irradiation device 3 irradiates the femtosecond pulse laser onto the focusing lens 31 at a position eccentrically by an eccentricity amount E from the lens central axis L1, and the irradiated femtosecond pulse laser is refracted by the focusing lens 31 to irradiate the container 2. Nanoparticles are generated in the region irradiated by the femtosecond pulse laser. At this time, nanoparticles are generated not only at the focal position of the femtosecond pulse laser but also in the regions before and after it, so they are generated in a certain spatial region.

[0056] The color information acquisition device 4 is for acquiring color information of the base solvent 6, and for example, a CMOS camera is used. The color information acquisition device 4 may acquire the overall color of the base solvent 6 irradiated with a femtosecond pulsed laser as color information, or it may acquire the color of the irradiated area of ​​the base solvent 6 irradiated with a femtosecond pulsed laser as color information. The color information acquisition device 4 acquires the color information of the base solvent 6 in terms of R (red), G (green), and B (blue) values. The color information acquisition device 4 may also acquire the color information of the base solvent 6 in terms of spectral characteristics of reflection, transmission, scattered light, and absorption.

[0057] Figure 5(a) is a schematic diagram showing an example of the configuration of the management device 1. As the management device 1, a known electronic device such as a personal computer (PC) can be used. The management device 1 includes, for example, a housing 10, a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a storage unit 104, and I / F 105~108, and may also include, for example, communication equipment. Each component 101~108 is connected by an internal bus 110.

[0058] The CPU 101 controls the entire management device 1. The ROM 102 stores the operation code of the CPU 101. The RAM 103 is a work area used when the CPU 101 is operating. The storage unit 104 stores various information such as a string database. As the storage unit 104, known data storage media such as an SD memory card, an HDD (Hard Disk Drive), or an SSD (Solid State Drive) can be used.

[0059] I / F106 is a known interface for sending and receiving various types of information with an input device 112, which is connected depending on the application. An input device such as a keyboard is used as the input device 112. Administrators, etc., input or select various types of information, or control commands for the illumination device 3 or the color information acquisition device 4, via the input device 112.

[0060] I / F107 is a known interface for sending and receiving various types of information with the display unit 113, which is connected depending on the application. The display unit 113 outputs various types of information stored in the storage unit 104, the processing status of the management device 1, etc. For example, a display can be used as the display unit 113, and it may also be a touch panel type. In this case, the display unit 113 may be configured to include an input device 112.

[0061] I / F108 is a known interface for transmitting and receiving various types of information with external devices such as container 2, irradiation device 3, and color information acquisition device 4. Multiple I / F108s may be provided and used to transmit and receive various types of information via a communication network such as the Internet.

[0062] Furthermore, the same interface may be used for I / F106 to I / F108, or multiple interfaces may be used for each of I / F106 to I / F108.

[0063] Figure 5(b) is a schematic diagram showing an example of the functions of the management device 1. The management device 1 comprises an acquisition unit 11, a processing unit 12, a storage unit 13, and an output unit 14. The functions shown in Figure 5(b) are realized by the CPU 101 executing programs stored in the storage unit 104, etc., using the RAM 103 as a working area.

[0064] The acquisition unit 11 acquires various types of information. The acquisition unit 11 acquires the color information of the basic solvent 6 acquired by the color information acquisition device 4. The acquisition unit 11 may also acquire the color information of the basic solvent as observed visually.

[0065] The processing unit 12 processes various information. The processing unit 12 has a setting unit 121. The setting unit 121 sets the irradiation conditions of the irradiation device 3 based on the color information acquired by the acquisition unit 11. The setting unit 121 may also set the irradiation conditions based on the change in the color information of the basic solvent 6. The change in the color information of the basic solvent 6 may be, for example, the sum of the squares of the differences between the RGB values ​​acquired as color information and the RGB values ​​for a specific color, or the difference in color information obtained by visual observation may be used. The irradiation conditions include light intensity conditions, scanning conditions, focusing conditions, and stirring conditions.

[0066] The light intensity conditions include conditions related to the light intensity of the femtosecond pulsed laser. The light intensity conditions also include, for example, conditions related to the incident diameter of the femtosecond pulsed laser.

[0067] The scanning conditions include conditions related to the scanning trajectory of the femtosecond pulsed laser being irradiated. The scanning conditions also include conditions related to whether or not the femtosecond pulsed laser is scanned. If the femtosecond pulsed laser is scanned, the conditions include conditions related to the scanning direction, such as a circular trajectory, vertical scanning, and horizontal scanning. It also includes conditions related to the radius of the circular trajectory and the scanning amount in the vertical and horizontal directions.

[0068] The focusing conditions include conditions related to the focusing of the femtosecond pulsed laser being irradiated. The focusing conditions include the type of focusing lens 31, the focal length, etc. The focusing conditions include, for example, focusing the femtosecond pulsed laser with the focusing lens 31 and converting it into a soft-focus beam such as a top-hat beam near the focusing position.

[0069] The stirring conditions include conditions related to the stirring of the basic solvent 6. The stirring conditions include, for example, conditions related to whether or not stirring is performed by the stirring bar 21, the size of the stirring bar 21, the stirring speed of the stirring bar 21, etc.

[0070] The setting unit 121 may set the irradiation conditions by comparing at least two locations in the overall color information of the basic solvent 6. The setting unit 121 may also set the irradiation conditions by comparing the irradiated area of ​​the basic solvent 6 with the unirradiated area of ​​the basic solvent 6 with the irradiated area of ​​the basic solvent 6 with the irradiated area of ​​the basic solvent 6 with the irradiated area with the irradiated area.

[0071] The setting unit 121 can also generate a determination result based on the color information acquired by the acquisition unit 11, indicating whether the light intensity of the irradiated femtosecond pulse laser falls into either the high light intensity region or the low light intensity region. The setting unit 121 can also generate a determination result based on the color information acquired by the acquisition unit 11, indicating whether the light intensity of the irradiated femtosecond pulse laser falls into any of the first to fourth regions. The setting unit 121 may set the irradiation conditions of the irradiation device 3 based on these determination results.

[0072] The memory unit 13 stores various types of information in the storage unit 104, or retrieves various types of information from the storage unit 104. The memory unit 13 stores or retrieves various types of information according to the processing content of the acquisition unit 11, the processing unit 12, and the output unit 14.

[0073] The output unit 14 outputs various information to the display unit 113, etc.

[0074] <First example of a method for manufacturing nanoparticles> Next, a first example of a method for producing nanoparticles will be described. As shown in Figure 6, the method for producing nanoparticles includes a production step S100 in which a femtosecond pulse laser is irradiated onto a basic solvent 6 in which metal ions are dissolved, for example, to produce nanoparticles containing metals or the like.

[0075] The generation process S100 includes an irradiation process S110 in which a femtosecond pulse laser is irradiated onto the base solvent 6, an acquisition process S120 in which color information of the base solvent 6 irradiated with the femtosecond pulse laser is acquired, and a setting process S130 in which the irradiation conditions of the femtosecond pulse laser are set based on the color information.

[0076] For example, as shown in Figure 7(a), in the irradiation step S110, when irradiating with a femtosecond pulsed laser, the light emitted from the femtosecond pulsed laser can be focused in the basic solvent 6 by the focusing lens 31. The femtosecond pulsed laser, incident on the focusing lens 31 as a parallel beam, is focused on the lens central axis L1 (optical axis) of the focal plane of the focusing lens 31. For example, as shown in Figure 7(b), the lens central axis L1 of this focusing lens 31 is positioned eccentrically from the rotation central axis C1 of the hollow rotary actuator. By rotating the focusing lens 31, the irradiation area of ​​the femtosecond pulsed laser can be changed. Note that the focusing lens 31 does not necessarily have to be rotated.

[0077] As shown in Figure 8(a), the lens central axis L1 of the focusing lens 31 is positioned eccentrically from the rotation central axis C1 of the hollow rotary actuator. Therefore, the lens central axis L1 of the focusing lens 31 moves in a circular orbit. As a result, as shown in Figure 8(b), the femtosecond pulse laser can scan along a circular orbit T with radius E. After being focused at the focusing position, the femtosecond pulse laser propagates so as to diverge from the normal from the rotation central axis C1 of the hollow rotary actuator (the extension of the principal ray at the time of incidence of the femtosecond pulse laser). It is also possible to irradiate only a predetermined area of ​​the basic solvent 6 without changing the irradiation area of ​​the femtosecond pulse laser.

[0078] Furthermore, in the irradiation step S110, the basic solvent 6 can be stirred with the stirring bar 21 while irradiating with the femtosecond pulse laser. The focusing position of the femtosecond pulse laser is positioned on the irradiation device 3 side of the rotational center axis C2 of the stirring bar 21. Note that stirring the basic solvent 6 is not necessarily required at the stage of determination before nanoparticles are formed and before the mixture is colored by LSPR.

[0079] Next, in acquisition step S120, for example, the acquisition unit 11 acquires color information of the irradiation area of ​​the basic solvent 6 in the irradiation area irradiated by the femtosecond pulse laser. The color information may be acquired, for example, via the color information acquisition device 4, or by visual inspection by an operator.

[0080] Next, in setting step S130, for example, the setting unit 121 sets the irradiation conditions for the femtosecond pulse laser based on the acquired color information. If white light is observed in the irradiation area in the acquired color information, the optical Kerr effect occurs, and it can be determined that the irradiated femtosecond pulse laser has a light intensity in the high light intensity region, which is the fourth region. If white light is not observed in the irradiation area in the acquired color information, the optical Kerr effect does not occur, and it can be determined that the irradiated femtosecond pulse laser has a light intensity in the low light intensity region, which is the first to third regions. In setting step S130, for example, the irradiation conditions for the femtosecond pulse laser can be set based on the determination result. The irradiation conditions may be set by the operator based on the acquired color information, or they may be set by the setting unit 121.

[0081] Then, a femtosecond pulsed laser with set irradiation conditions is irradiated onto the base solvent 6 to generate nanoparticles.

[0082] The method for producing nanoparticles is thus completed. Note that at least one of the above steps, the irradiation step S110, the acquisition step S120, and the setting step S130, may be performed multiple times.

[0083] The nanoparticle manufacturing method in this embodiment includes a production step S100 in which a femtosecond pulsed laser is irradiated onto a basic solvent 6 containing a precursor to generate nanoparticles (e.g., metal nanoparticles). The production step S100 includes an irradiation step S110 in which a femtosecond pulsed laser is irradiated onto the basic solvent 6, an acquisition step S120 in which color information of the basic solvent 6 irradiated with the femtosecond pulsed laser is acquired, and a setting step S130 in which the irradiation conditions of the femtosecond pulsed laser are set based on the color information. In other words, by using the color information of the basic solvent as an indicator of the nanoparticle production state, irradiation conditions suitable for nanoparticle production can be easily set or changed. This makes it possible to improve the production efficiency of nanoparticles.

[0084] In this embodiment, setting step S130 sets irradiation conditions, including the light intensity conditions of the femtosecond pulsed laser. This improves the accuracy of setting the irradiation conditions, thereby further improving the manufacturing efficiency of nanoparticles.

[0085] For example, in the case of a solvent containing water as the base solvent 6, irradiation with a femtosecond pulsed laser decomposes the water molecules constituting the base solvent 6, generating hydrogen radicals, free electrons, and hydroxyl radicals. Of these, the hydrogen radicals and free electrons are used in the reduction reaction of alloy nanoparticles, but at the same time, oxygen and hydrogen gases are generated. The generation of these oxygen and hydrogen gases scatters the incident light, leading to a decrease in light intensity at the focal point.

[0086] In this embodiment, the setting step S130 sets irradiation conditions, including stirring conditions for stirring the basic solvent 6. For example, if there is a difference in color (uneven coloring) when comparing at least two locations in the overall color information of the basic solvent 6, stirring conditions for stirring the basic solvent 6 can be set based on the color information. As the basic solvent 6 is stirred in accordance with the setting of the stirring conditions, gases such as oxygen and hydrogen generated in the light irradiation area are swept away, and multiple metal ions can be efficiently supplied to the irradiation area. This makes it possible to further improve the production efficiency of nanoparticles.

[0087] Furthermore, in this embodiment, setting step S130 sets irradiation conditions, including scanning conditions for scanning the femtosecond pulsed laser. For example, if there is a difference in color (color unevenness) when comparing at least two locations in the overall color information of the basic solvent 6, scanning conditions for scanning the femtosecond pulsed laser can be set based on the color information. In conjunction with setting the scanning conditions, the irradiation area of ​​the femtosecond pulsed laser can be changed. If the irradiation area is not changed, once nanoparticles are produced, multiple metal ions will no longer be present in that area (because they have been transformed into nanoparticles). Therefore, by changing the irradiation area and irradiating an area where nanoparticles have not yet been produced, the amount of multiple metal ions present in the irradiation area of ​​the femtosecond pulsed laser can be kept constant. As a result, the manufacturing efficiency of nanoparticles can be further improved.

[0088] <Second example of a method for manufacturing nanoparticles> Next, a second example of a method for producing nanoparticles will be described. Similar to the first example described above, the second example of a method for producing nanoparticles includes a production step S100 in which a femtosecond pulsed laser is irradiated onto a basic solvent 6 in which metal ions are dissolved, for example, to produce nanoparticles.

[0089] To execute a process efficiently, it is necessary to detect its completion with high accuracy. A system for detecting process completion is called an "endpoint monitor," and to achieve this function, it is possible to use "color information" detected in the third region of Figure 1, for example.

[0090] In detail, in the second example of the nanoparticle manufacturing method, first, an irradiation step S110 is performed in which a femtosecond pulse laser is irradiated onto the basic solvent 6.

[0091] In the irradiation step S110, the irradiation device 3 irradiates the base solvent 6 contained in the container 2 with a femtosecond pulsed laser under predetermined irradiation conditions. Nanoparticles are generated by the nonlinear effect caused by irradiating the base solvent 6, in which metal ions are dissolved, with a femtosecond pulsed laser. Then, in accordance with the amount of these nanoparticles, the base solvent 6 becomes colored and transparent as the irradiation time progresses due to the LSPR described above.

[0092] In the acquisition process S120, the color information acquisition device 4 acquires the color information of the basic solvent 6 at each irradiation time under a predetermined light intensity, and the acquisition unit 11 acquires the color information of the basic solvent 6 from the color information acquisition device 4. As the color information of the basic solvent 6, RGB values ​​such as R196:G89:B83 are acquired. When acquiring color information, if reflected, transmitted, or scattered light is received, the received light intensity changes due to changes in the absorption characteristics of the basic solvent 6. In order to acquire color information without being affected by this change, high-precision measurement is possible by using normalized values ​​obtained by dividing the R, G, and B values ​​by a constant value, in this case 100, where the sum of R, G, and B is a constant value. For example, the measured value acquired as R100:G45:B42 may be processed as normalized color information of R54:G24:B22.

[0093] Then, in setting step S130, the irradiation conditions for the femtosecond pulse laser are set based on the changes in the acquired color information.

[0094] The color information at the beginning of the process, for example, starts from a colorless state, and as nanoparticles are generated, the color gradually changes to, for example, red, orange, brown, etc. When the reduction of metal ions in the basic solvent 6 is complete, no new nanoparticles are generated, and at the same time, the color change stops, resulting in a "specific color". Therefore, the arrival of this "specific color" signifies the end of the process. Consequently, this "specific color" information can be used as an endpoint monitor. In addition to setting the color information corresponding to the endpoint monitor as the "specific color," it is also possible to set the color information during the color change, or any arbitrary color information.

[0095] When generating nanoparticles using a femtosecond pulsed laser, the integrated light intensity required for the basic solvent 6 to be colored to a specific color can be expressed as the product of, for example, the nanoparticle production efficiency and the irradiation time of the femtosecond pulsed laser. For example, Figure 9 is a conceptual diagram showing the relationship between the light intensity per unit area of ​​the femtosecond pulsed laser and the integrated light intensity of the femtosecond pulsed laser. For example, as shown in the second and third regions of Figure 9, there are regions where the integrated light intensity required for the basic solvent 6 to be colored to a specific color decreases as the light intensity per unit area increases.

[0096] For example, increasing the light intensity within the second region gradually decreases the cumulative intensity required to produce a "specific color." Furthermore, increasing the light intensity beyond the second region, within the third region, results in little to no variation in the cumulative intensity required to produce a "specific color." By focusing on this lack of variation in irradiation time, the light intensity that falls within the second region can be determined. Specifically, by calculating the cumulative intensity required to produce a "specific color" at different light intensities, if there is a difference in these cumulative intensities, the light intensity must be at least within the second region. The appropriate difference in cumulative intensity can be determined experimentally, taking into account the reproducibility of the measurements. Since the relationship between the irradiation conditions of the femtosecond pulse laser and the cumulative intensity changes depending on the nanoparticles being manufactured, the relationship between irradiation conditions and cumulative intensity is determined according to the nanoparticles.

[0097] Thus, in the setting step S130, the irradiation conditions for the femtosecond pulse laser irradiating the basic solvent 6 are set based on the change in color information. Specifically, the light intensity of the second or third region that corresponds to the "specific color" in Figure 1 described above is determined based on the change in color information. Then, based on this determination result, the irradiation conditions for the femtosecond pulse laser irradiating the basic solvent 6 are set. The setting of the irradiation conditions may be done by an operator based on the time change of the acquired color information, or it may be set by the setting unit 121.

[0098] Then, a femtosecond pulsed laser with set irradiation conditions is irradiated onto the base solvent 6 to generate nanoparticles.

[0099] This completes the method for manufacturing nanoparticles.

[0100] In addition, the setting step S130 may refer to the relationship between the irradiation conditions and integrated intensity of the femtosecond pulsed laser, which has been determined in advance, and set the irradiation conditions of the femtosecond pulsed laser based on the change in color information. At this time, the relationship between the irradiation conditions and integrated intensity of the femtosecond pulsed laser, which has been determined in advance, is referred to, and it is determined based on the change in color information whether the light intensity corresponds to one of the light intensity regions 1 to 4. Then, the irradiation conditions of the femtosecond pulsed laser can be set based on this determination result.

[0101] Furthermore, the irradiation conditions may include focusing conditions, scanning conditions, stirring conditions, etc. In this case, it is sufficient to understand the relationship between the irradiation conditions such as focusing conditions, scanning conditions, and stirring conditions of the femtosecond pulsed laser and the integrated intensity.

[0102] For example, in acquisition step S120, the acquisition unit 11 may acquire color information of the basic solvent 6 at each irradiation time when a femtosecond pulse laser is irradiated under a predetermined light intensity, using the focusing conditions as a parameter.

[0103] For example, in acquisition step S120, the acquisition unit 11 may acquire color information of the basic solvent 6 when irradiated with a femtosecond pulse laser under a predetermined light intensity, using scanning conditions as a parameter, for each irradiation time. For example, the circular orbit that the femtosecond pulse laser scans may be used as the parameter, and color information of the basic solvent 6 may be acquired for each irradiation time.

[0104] For example, in acquisition step S120, the acquisition unit 11 may acquire color information of the basic solvent 6 when irradiated with a femtosecond pulse laser under a predetermined light intensity, using stirring conditions as a parameter, for each irradiation time. Alternatively, the presence or absence of stirring of the basic solvent 6, the size of the stirring bar, and the stirring speed may be used as parameters to acquire color information of the basic solvent 6 for each irradiation time.

[0105] Then, in setting step S130, the irradiation conditions of the femtosecond pulse laser are set based on the acquired color information. At this time, the irradiation conditions should be set by referring to the relationship between the irradiation conditions of the femtosecond pulse laser and the integrated intensity.

[0106] In this embodiment, the setting step S130 sets the irradiation conditions of the femtosecond pulse laser based on the change in the color information of the basic solvent 6. This improves the accuracy of setting the irradiation conditions, thereby further improving the manufacturing efficiency of nanoparticles.

[0107] In this embodiment, the setting step S130 sets the irradiation conditions for the femtosecond pulse laser based on color information that results in a "specific color" with little to no color change, based on the change in color information of the basic solvent 6. This allows for endpoint monitoring. As a result, it becomes possible to further improve the manufacturing efficiency of nanoparticles.

[0108] <Third example of a method for manufacturing nanoparticles> Next, a third example of a method for producing nanoparticles will be described. The third example of a method for producing nanoparticles further comprises an evaluation step S200 for evaluating the nanoparticles. The evaluation step S200 is performed, for example, after the production step S100.

[0109] The evaluation step S200 evaluates, for example, the solid solubility of the nanoparticles. "Solid solubility" indicates the degree to which multiple materials contained in the nanoparticles are uniformly present within the particle. By using "solid solubility," it is possible to show the difference between nanoparticles PA containing materials A1 and A2 and nanoparticles PB containing materials B1 and B2, for example, as shown in Figures 10(a) and 10(b). This makes it possible to evaluate the state of existence of the materials contained in the nanoparticles.

[0110] The evaluation step S200 evaluates the state of existence of multiple materials contained in the nanoparticles. The evaluation step S200 comprises, for example, an observation step S210, a detection step S220, and a comparison step S230, as shown in Figure 11.

[0111] <Observation process S210> In observation step S210, as shown in Figure 12 for example, nanoparticles are observed and particle images of the nanoparticles are acquired. In observation step S210, particle images can be acquired by observing the nanoparticles using, for example, a scanning transmission electron microscope (STEM). In this case, the degree of solid solubility for each material can be observed with higher precision compared to other methods of acquiring particle images. In addition to the above, a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) may also be used in observation step S210. The following describes the case using a STEM, particularly a HAADF-STEM.

[0112] For example, when observing nanoparticles using a STEM, a basic solvent 6 containing nanoparticles is dropped onto a microgrid with a carbon support film to immobilize the nanoparticles. This allows for the acquisition of particle images using the scanning transmission electron microscope mentioned above.

[0113] <Detection process S220> The detection step S220 obtains detection results that show the relationship between the detection intensity of multiple materials contained in the particle image and their detection positions. In the detection step S220, the detection results can be obtained using known elemental analysis methods, such as energy dispersive X-ray spectroscopy (EDS).

[0114] The detection step S220 may acquire detection results for, for example, one particle captured in the particle image (for example, the particle within the dashed frame in Figure 12), or it may acquire detection results for multiple particles. The detection step S220 may acquire detection results after acquiring the particle image, or it may acquire detection results simultaneously with the particle image. In other words, the timing of the observation step S210 and the detection step S220 can be arbitrarily set according to the equipment used in each step.

[0115] The detection step S220 acquires a detection image showing the detection intensity at each detection position in a two-dimensional direction for the particle image, for example. In this case, the detection result is obtained that shows the relationship between the detection intensity (white circles, black circles) of each material A1 and A2 and the detection position (position X, position Y), as shown in Figures 13(a) and 13(b), for example.

[0116] In addition to the above, the detection step S220 acquires detection results that show the detection intensity at each detection position in the one-dimensional direction for the particle image, for example. In this case, the detection results acquire detection results that show the relationship between the detection intensity (Intensity) of each material A1 and A2 and the detection position (position X), as shown in Figures 14(a) and 14(b). The detection results based on the one-dimensional direction correspond to the detection intensity along the AA line in the two-dimensional detection results shown in Figures 14(c) and 14(d). Note that the detection position in the detection results based on the one-dimensional direction may be in the direction along the AA line (position X) as described above, or in the direction intersecting the AA line (for example, position Y), and is arbitrary.

[0117] For example, in the detection step S220, the detection result may be obtained by performing an approximation method on the relationship between the detection intensity and the detection position. In this case, as shown in Figures 15(a) and 15(b), for example, the detection result will show the approximation result of performing an even function approximation on the detection intensity at each detection position in the one-dimensional direction. This makes it possible to suppress the decrease in comparison accuracy described later, even when the particle image contains noise, etc. The function used as the approximation method may be an even function or a known function whose position can be uniquely determined. The function used as the approximation method may be, for example, a Gaussian function or a function like the one in equation (1) below. Y=SQRT(r 2 -X 2 ) (1)

[0118] For example, in the detection step S220, the detection result may be obtained as the result of smoothing, which is the result of averaging the relationship between the detection intensity and the detection position. This makes it possible to suppress the decrease in comparison accuracy described later, even when the particle image contains noise, etc. The range of the detection position when performing averaging can be set arbitrarily according to the application.

[0119] <Comparison process S230> In the comparison step S230, the relationship between the detection intensity and the detection position is compared for each of the multiple materials based on the detection results. In the comparison step S230, the degree of solid solubility of each material contained in the nanoparticles can be quantitatively evaluated based on the comparison results for each of the multiple materials.

[0120] The comparison step S230 compares, for example, the characteristics of the detection intensity distribution in the detection results for multiple materials. Then, the comparison step S230 obtains the degree of deviation of the characteristics of the detection intensity distribution for each material as the comparison result. In this case, for example, a comparison result with a small degree of deviation indicates good solid solubility, and a comparison result with a large degree of deviation indicates poor solid solubility.

[0121] For example, as shown in Figure 10(b), nanoparticle PB has areas where material B2 is densely concentrated (for example, within the dashed frame in Figure 10(b)). In contrast, as shown in Figure 10(a), for example, nanoparticle PA has a more uniform distribution of material A2 compared to nanoparticle PB. In this case, the degree of separation of materials A1 and A2 in nanoparticle PA tends to be smaller than the degree of separation of materials B1 and B2 in nanoparticle PB. Therefore, in the comparison step S230, the solid solubility of nanoparticle PA can be evaluated as better than that of nanoparticle PB.

[0122] Furthermore, the degree of solid solubility may indicate not only the relative degree described above, but also, for example, a degree based on a predetermined threshold. In addition, the degree of solid solubility may be expressed not only as the two values ​​of "good" and "bad" described above, but also as a numerical value such as a percentage or a multi-level scale. As a specific value, for example, if expressed as a percentage normalized by particle size, 5% or less may be considered "good".

[0123] For example, as shown in Figures 13(a) and 13(b), if detection results are obtained based on two-dimensional directions, the comparison step S230 may compare the detection intensity of each material A1 and A2 for each detection position. In this case, the comparison result will show the degree of deviation obtained by comparing, for example, the characteristics of the distribution of detection intensity in each material A1 and A2. By obtaining a comparison result showing the degree of deviation, the degree of solid solubility can be quantitatively evaluated. The degree of deviation can be obtained using known processing techniques such as matching processing.

[0124] For example, the comparison step S230 may include in the comparison results the results obtained by deriving the content of each material based on the detection results based on two dimensions. Alternatively, the comparison step S230 may consider the results obtained by counting the frequency of detection intensities included in the detection range in the detection results for each material as the content of each material.

[0125] For example, the comparison step S230 compares the detection positions associated with the maximum detection intensity in the approximate results for each of several materials. The comparison step S230 identifies the detection positions (A1t, A2t, B1t, B2t) associated with the maximum detection intensity, as shown in Figures 16(a) and 16(b), for example. Subsequently, the comparison step S230 compares the detection positions for each material contained in the nanoparticles (nanoparticle PA or nanoparticle PB) (material A1 and material A2 for nanoparticle PA, and material B1 and material B2 for nanoparticle PB). As a result of this comparison, the degree of deviation Ad is obtained in the case of nanoparticle PA, and the degree of deviation Bd is obtained in the case of nanoparticle PB.

[0126] The deviation degrees Ad and Bd obtained from the above comparison correspond to the states of existence of materials A1, A2, B1, and B2, for example, shown in Figures 10(a) and 10(b). Therefore, the deviation degree Ad is smaller than the deviation degree Bd, and the solid solubility of nanoparticle PA can be evaluated as being better than that of nanoparticle PB.

[0127] Although the above explanation described the case where approximate results were obtained as the detection result, the same processing and evaluation of the degree of solid solubility can be performed even when smoothing results are obtained as the detection result.

[0128] In addition to the above, for example, the comparison step S230 may compare the spatial frequencies based on the detection results for each of the multiple materials. In this case, the difference in the content of each material contained in the nanoparticles can be derived from the difference in spatial frequencies. For example, if there are components with low spatial frequencies, the probability of the material being present at each detection position can be considered high, and therefore the content can be judged to be high. Conversely, as the presence of components with high spatial frequencies increases, the probability of the material being present at each detection position decreases, and therefore the content can be judged to be low. For this reason, by combining the degree of deviation described above with the comparison of spatial frequency components, it becomes possible to evaluate the degree of solid solubility considering the content.

[0129] Furthermore, the degree of solid solubility of nanoparticles is defined as the difference between the processed signal obtained by applying even-function approximation to the profile signal from STEM observation and the center of each material, as described above.

[0130] The comparison step S230 may include, for example, a measurement step and an accuracy verification step. The measurement step may be performed, for example, before the observation step S210 or before the detection step S220, and is optional. The accuracy verification step is performed after obtaining the comparison results described above.

[0131] The measurement process involves measuring the content of each of several materials using X-ray diffraction. X-ray diffraction can be performed using a known X-ray diffraction apparatus.

[0132] The accuracy verification step evaluates the accuracy of the comparison results in the comparison step S230 based on the measurement results in the measurement step. For example, the content derived in the comparison step S230 is compared with the content measured using the X-ray diffraction method. Here, the content derived in the comparison step S230 is derived from specific particles and therefore does not take into account the variation between individual particles. In contrast, the content measured using the X-ray diffraction method is a measurement result from multiple particles and can therefore be considered as the content of all nanoparticles. For this reason, the accuracy of the content derived in the comparison step S230 can be evaluated using the content measured in the measurement step as a reference.

[0133] This generates the nanoparticles in this embodiment. When performing at least one of the above steps, for example, the control device 1 may be used, or known processing techniques using electronic equipment may be used.

[0134] According to this embodiment, the comparison step S230 compares the relationship between the detection intensity and the detection position for each of several materials based on the detection results. This makes it possible to quantitatively evaluate the degree of solid solubility of each material contained in the nanoparticles. This makes it possible to clearly determine the quality of the nanoparticles.

[0135] Furthermore, according to this embodiment, the observation step S210 acquires particle images using a scanning transmission electron microscope. Therefore, compared to other methods for acquiring particle images, the degree of solid solubility for each material can be acquired with high accuracy. This makes it possible to evaluate the degree of solid solubility with high accuracy.

[0136] Furthermore, according to this embodiment, the detection step S220 obtains an approximate result as the detection result by performing an approximation method on the relationship between the detection intensity and the detection position. Therefore, even when the shape of the nanoparticles differs from a perfect sphere to a sub-nanometer value in the profile signal of the particle image, a decrease in comparison accuracy can be suppressed. This makes it possible to achieve stable evaluation of the degree of solid solubility.

[0137] Furthermore, according to this embodiment, the comparison step S230 compares the detection position associated with the maximum detection intensity in the approximate results for each of the multiple materials. Therefore, it is possible to easily evaluate the differences in the bias of the degree of solid solubility for each material contained in the nanoparticles. This makes it possible to easily evaluate the degree of solid solubility.

[0138] Furthermore, according to this embodiment, the comparison step S230 compares the spatial frequencies based on the detection results for each of the multiple materials. Therefore, the differences in the content of each material contained in the nanoparticles can be easily evaluated. This makes it possible to evaluate the degree of solid solubility while taking the content into account.

[0139] Furthermore, according to this embodiment, the accuracy verification step evaluates the accuracy of the comparison results in the comparison step S230 based on the measurement results in the measurement step. That is, the accuracy of the comparison results, which compare the state of existence of each material contained in a part of the nanoparticles, is evaluated using the measurement results that show the content rate of each material contained in the entire nanoparticle. Therefore, it is possible to evaluate whether or not the comparison results are valid as characteristics of the entire nanoparticle. This makes it possible to efficiently evaluate the degree of solid solubility of the nanoparticles.

[0140] (Second Embodiment) In the nanoparticle manufacturing system 100 according to the second embodiment, as shown in Figure 17(a), an irradiation device 3, a focusing lens 31, and a wedge prism 33 are provided.

[0141] The wedge prism 33 is positioned between the irradiation device 3 and the focusing lens 31. The wedge prism 33 is rotatable by a hollow rotary actuator (not shown). As shown in Figure 17(b), the irradiation area of ​​the femtosecond pulse laser can be changed by rotating the wedge prism 33.

[0142] In the irradiation device 3, when a femtosecond pulse laser with a parallel beam of light is incident on the wedge prism 33, according to Snell's law, it becomes a parallel ray tilted by a predetermined angle based on the wedge size and the refractive index of the glass material. When this tilted parallel ray is focused by the condensing lens 31, it is focused at the focal plane as an off-axis image height. The off-axis image height Y is determined by the tilt angle θ and the focal length f of the imaging lens (E=ftanθ). By rotating this wedge prism 33, it is possible to scan a circle whose radius is the off-axis image height Y. By positioning the wedge prism 33 at the front focal position of the condensing lens 31 (= to the left of the condensing lens 31 in Figures 17(a) and 17(b)), a telecentric optical system is configured with the exit pupil at infinity, and the principal ray of the focused light is approximately parallel to the optical axis.

[0143] When the wedge prism 33 is shifted in the direction of the optical axis from the front focal position of the condensing lens 31, the optical system becomes different from a telecentric optical system. Shifting it to the left in the diagram causes the principal rays to propagate in a convergent manner, while shifting it to the right causes the principal rays to propagate in a divergent manner. This divergent propagation state is the same as the light propagation state in a configuration using an "eccentric condensing lens".

[0144] The femtosecond pulsed laser focused in the basic solvent 6 has the smallest spot and the highest intensity per unit area at the focal point. At positions offset in the front and back of the optical axis, the femtosecond pulsed laser spreads out, and nanoparticles are generated in the areas irradiated by the femtosecond pulsed laser. Thus, nanoparticles are generated not only at the focal point but also in the front and back regions, resulting in generation across a certain spatial region.

[0145] In this embodiment, setting step S130 sets irradiation conditions, including scanning conditions for scanning the femtosecond pulsed laser. For example, if there is a difference in color (color unevenness) when comparing at least two locations in the overall color information of the basic solvent 6, scanning conditions for scanning the femtosecond pulsed laser can be set based on the color information. In conjunction with setting the scanning conditions, the irradiation area of ​​the femtosecond pulsed laser can be changed. If the irradiation area is not changed, when nanoparticles are produced, multiple metal ions will no longer be present in that area (because they have been transformed into nanoparticles). Therefore, by changing the irradiation area and irradiating an area where nanoparticles have not yet been produced, the amount of multiple metal ions present in the irradiation area of ​​the femtosecond pulsed laser can be kept constant. As a result, the nanoparticle production efficiency can be further improved.

[0146] (Third embodiment) In the nanoparticle manufacturing system 100 according to the third embodiment, as shown in Figures 18(a) and 18(b), an irradiation device 3, a focusing lens 31, a laser top-hat converter 34, and a spectrometer 35 are provided.

[0147] The laser top-hat converter 34 converts a femtosecond pulsed laser emitted from the irradiation device 3 as a Gaussian beam into a top-hat beam. By using the laser top-hat converter 34, the light intensity in the top-hat portion of the femtosecond pulsed laser can be made uniform. Instead of the laser top-hat converter 34, an optical system with aberration correction that converts a femtosecond pulsed laser emitted from the irradiation device 3 as a Gaussian beam into a soft-focus beam may be used.

[0148] The spectrometer 35 splits the irradiated femtosecond pulse laser into two or more wavelengths. The spectrometer 35 includes a half mirror 36, a first reflector 37, a second reflector 38, and a third reflector 39. The half mirror 36 reflects light of a specific wavelength and transmits light of other wavelengths.

[0149] As shown in Figure 18(a), the first reflector 37, the second reflector 38, and the third reflector 39 control the position at which light is reflected and irradiated onto the basic solvent 6. The first reflector 37 is a reflector that directs the femtosecond pulsed laser, which has been converted into a top-hat beam via the laser top-hat converter 34, to the half-mirror 36. The second reflector 38 is a reflector that reflects the femtosecond pulsed laser that has passed through the half-mirror 36. The third reflector 39 is a reflector that reflects the femtosecond pulsed laser that has been reflected off the half-mirror 36.

[0150] As shown in Figure 18(b), the femtosecond pulsed laser that has been reflected by the second reflector 38 and passed through the half mirror 36 is irradiated onto the base solvent 6 contained in the container 2 via the focusing lens 31. Similarly, the femtosecond pulsed laser reflected by the half mirror 36, which has been reflected by the third reflector 39, is also irradiated onto the base solvent contained in the container 2 via the focusing lens 31. Thus, the spectrometer 35 may irradiate the spectrally separated femtosecond pulsed lasers onto the base solvent 6 contained in different containers 2. This allows for the production of nanoparticles by irradiating the base solvent 6 in different containers 2 with femtosecond pulsed lasers. Therefore, it is possible to improve the efficiency of nanoparticle production.

[0151] Furthermore, as shown in a magnified view in Figure 18(b), by using the laser top-hat converter 34, the femtosecond pulsed laser irradiated onto the base solvent 6 can have its light intensity homogenized near the focal point.

[0152] Although not shown in the diagram, the spectrometer 35 may irradiate the basic solvent 6 contained in a single container 2 with the spectrally separated femtosecond pulsed lasers. This allows for the production of nanoparticles in the basic solvent 6 contained in a single container using multiple irradiation regions. This makes it possible to improve the efficiency of nanoparticle production.

[0153] The setting unit 121 sets the presence and type of the laser top hat converter 34 as focusing conditions. The setting unit 121 sets conditions related to controlling the wavelength of light reflected and transmitted by the half mirror 36 as focusing conditions. The setting unit 121 sets the angles of the first reflector 37, second reflector 38, and third reflector 39 as focusing conditions.

[0154] Next, the method for manufacturing nanoparticles will be described. In the irradiation step S110, the irradiation device 3 irradiates the basic solvent 6 contained in the container 2 with a femtosecond pulse laser under predetermined irradiation conditions.

[0155] Then, in acquisition step S120, the color information of the basic solvent 6 when irradiated with a femtosecond pulse laser is acquired for each irradiation time, using the focusing conditions as a parameter. The color information of the basic solvent 6 is acquired for each irradiation time, using parameters such as the type of focusing lens and whether or not it is converted to a top-hat beam near the focusing position.

[0156] Next, in setting step S130, the irradiation conditions for the femtosecond pulse laser are set based on the acquired color information or the time change of the color information.

[0157] Then, a femtosecond pulsed laser with set irradiation conditions is irradiated onto the base solvent 6 to generate nanoparticles.

[0158] In this embodiment, setting step S130 sets irradiation conditions including focusing conditions that focus the femtosecond pulsed laser with a focusing lens and convert it into a soft-focus beam near the focusing position. For example, if there are color differences (color unevenness) when comparing at least two locations in the overall color information of the basic solvent 6, the above scanning conditions can be set based on the color information. Then, in conjunction with setting the scanning conditions, the femtosecond pulsed laser is soft-focused. Unlike the light that spreads according to the numerical aperture value of the focus, the light spread, known as soft focus, is converted so that it does not spread regardless of the numerical aperture, thus making it possible to uniformize the light intensity near the focusing position of the femtosecond pulsed laser. As a result, the basic solvent 6 is irradiated uniformly with the femtosecond pulsed laser, making it possible to further improve the manufacturing efficiency of nanoparticles.

[0159] In this embodiment, setting step S130 sets irradiation conditions that include focusing conditions, which involve focusing the femtosecond pulsed laser with a focusing lens and converting it into a top-hat beam near the focusing position. That is, as the scanning conditions are set, the femtosecond pulsed laser is converted into a top-hat beam, which further uniformizes the light intensity near the focusing position of the femtosecond pulsed laser. As a result, the basic solvent 6 is irradiated uniformly with the femtosecond pulsed laser, making it possible to further improve the manufacturing efficiency of nanoparticles.

[0160] In this embodiment, setting step S130 involves spectrally analyzing a femtosecond pulsed laser and setting irradiation conditions that include focusing conditions for irradiating the spectrally analyzed femtosecond pulsed laser onto basic solvents 6 contained in different containers 2. For example, if at least two locations in the overall color information of the basic solvent 6 show color differences (color unevenness), the focusing conditions can be set based on the color information. Then, upon setting the focusing conditions, the femtosecond pulsed laser is spectrally analyzed, and the spectrally analyzed femtosecond pulsed laser is irradiated onto the basic solvents 6 contained in different containers 2. This makes it possible to further improve the manufacturing efficiency of nanoparticles.

[0161] (Fourth Embodiment) In the nanoparticle manufacturing system 100 according to the fourth embodiment, as shown in Figure 19, an irradiation device 3, a focusing lens 31, and galvanometer mirrors 131 and 132 are provided.

[0162] The galvano mirror 131 can scan the femtosecond pulsed laser irradiated from the irradiation device 3 in the left-right direction relative to the base solvent 6. The galvano mirror 132 can scan the femtosecond pulsed laser irradiated from the irradiation device 3 in the up-down direction relative to the base solvent 6.

[0163] The setting unit 121 can set scanning conditions, such as whether to scan the femtosecond pulse laser in the vertical or horizontal direction. The setting unit 121 can also set scanning conditions such as the presence and type of galvanometer mirrors 131 and 132, and the reflection angle of the galvanometer mirrors 131 and 132.

[0164] Next, the method for manufacturing nanoparticles will be described. In the irradiation step S110, the irradiation device 3 irradiates the basic solvent 6 contained in the container 2 with a femtosecond pulse laser under predetermined irradiation conditions.

[0165] Then, in acquisition step S120, using the focusing conditions as a parameter, the color information of the basic solvent 6 when irradiated with a femtosecond pulse laser is acquired for each irradiation time.

[0166] Next, in setting step S130, the irradiation conditions for the femtosecond pulse laser are set based on the acquired color information or the time change of the color information.

[0167] Then, a femtosecond pulsed laser with set irradiation conditions is irradiated onto the base solvent 6 to generate nanoparticles.

[0168] In this embodiment, setting step S130 sets irradiation conditions, including scanning conditions for scanning the femtosecond pulsed laser. For example, if there is a difference in color (color unevenness) when comparing at least two locations in the overall color information of the basic solvent 6, scanning conditions for scanning the femtosecond pulsed laser can be set based on the color information. In conjunction with setting the scanning conditions, the irradiation area of ​​the femtosecond pulsed laser can be changed. If the irradiation area is not changed, when nanoparticles are produced, multiple metal ions will no longer be present in that area (because they have been transformed into nanoparticles). Therefore, by changing the irradiation area and irradiating an area where nanoparticles have not yet been produced, the amount of multiple metal ions present in the irradiation area of ​​the femtosecond pulsed laser can be kept constant. As a result, the nanoparticle production efficiency can be further improved.

[0169] The above-described embodiment proposes a method for optimizing the irradiation conditions of laser light in the "laser-induced nucleation method," which involves irradiating metal electrons dissolved in a solvent with a femtosecond pulsed laser as a method for producing nanoparticles.

[0170] The method for optimizing laser irradiation conditions using color information proposed in this invention is also effective, for example, when producing nanoparticles using the "liquid-phase laser ablation" method, in which a solid is irradiated with a femtosecond pulsed laser in a liquid.

[0171] Although examples of embodiments of the present invention have been described in detail above, the embodiments described above are merely examples of concrete implementations of the present invention, and the technical scope of the present invention should not be interpreted as being limited by them. [Explanation of Symbols]

[0172] 100: Nanoparticle manufacturing system 1: Management device 2: Container 21: Stirrer 3: Irradiation device 31: Focusing lens 33: Wedge Prism 34: Laser Top Hat Converter 35: Spectroscopic device 36: Half-mirror 37: 1st reflective material 38:Second reflective material 39:Third reflective material 131: Galvano Mirror 132: Galvano Mirror 4: Color information acquisition device 6: Basic Solvents S100: Generation process S110: Irradiation process S120: Acquisition process S130: Setting process S200: Evaluation Process S210: Observation process S220: Detection process S230: Comparative Engineering

Claims

1. The process includes a generation step in which a femtosecond pulsed laser is irradiated onto a basic solvent containing a precursor to generate nanoparticles. The aforementioned generation step is An irradiation step of irradiating the base solvent with the femtosecond pulse laser, An acquisition step to acquire color information of the basic solvent irradiated with the femtosecond pulse laser, A setting step of setting the irradiation conditions of the femtosecond pulse laser based on the aforementioned color information, Having A method for producing nanoparticles characterized by the following.

2. The setting step involves setting the irradiation conditions based on the change in the color information of the basic solvent. A method for producing nanoparticles according to claim 1, characterized by the above.

3. The setting step involves setting the irradiation conditions, including the light intensity conditions of the femtosecond pulsed laser. A method for producing nanoparticles according to claim 1 or 2, characterized by the above.

4. The setting step involves setting the irradiation conditions, including scanning conditions for scanning the femtosecond pulse laser. A method for producing nanoparticles according to claim 1 or 2, characterized by the above.

5. The setting step involves setting the irradiation conditions, which include focusing conditions that concentrate the femtosecond pulse laser using a focusing lens and convert it into a soft-focus beam near the focusing position. A method for producing nanoparticles according to claim 1 or 2, characterized by the above.

6. The setting step involves setting the irradiation conditions, which include stirring conditions for stirring the basic solvent. A method for producing nanoparticles according to claim 1 or 2, characterized by the above.

7. The system further includes an evaluation step for evaluating the state of existence of the material contained in the aforementioned nanoparticles. A method for producing nanoparticles according to claim 1, characterized by the above.

8. The aforementioned evaluation process is, An observation step of observing the aforementioned nanoparticles and obtaining a particle image, A detection step of obtaining a detection result that shows the relationship between the detection intensity of multiple materials included in the particle image and the detection position, Based on the detection results, a comparison step is performed to compare the relationship between the detection intensity and the detection position for each of the multiple materials. including A method for producing nanoparticles according to claim 7, characterized by the above.

9. The observation step involves acquiring the particle image using a scanning transmission electron microscope. A method for producing nanoparticles according to claim 8, characterized by the above.

10. The detection step involves obtaining an approximate result as the detection result by performing an approximation method on the relationship between the detection intensity and the detection position. A method for producing nanoparticles according to claim 8, characterized by the above.

11. The comparison step involves comparing the detection position associated with the maximum value of the detection intensity in the approximate result for each of the multiple materials. A method for producing nanoparticles according to claim 10, characterized by the above.

12. The comparison step involves comparing the spatial frequencies based on the detection results for each of the multiple materials. A method for producing nanoparticles according to claim 8, characterized by the above.

13. The aforementioned evaluation process is, A measurement step of measuring the content of each of the multiple materials using X-ray diffraction, A precision verification step is performed to evaluate the accuracy of the comparison results in the comparison step based on the measurement results in the measurement step, including A method for producing nanoparticles according to claim 8, characterized by the above.

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