A dynamic light scattering experimental device and method

Abstract

The application discloses a dynamic light scattering experimental device and method based on, and belongs to the field of material determination. The inner cavity of the experimental body of the device is used for placing a nano-particle solution to be measured; incident laser is input to a spectrometer sheet and is divided into probe light and reference light; the probe light is input to the first polarization state adjusting mechanism, is input to the experimental body from the first window through the first reflecting mirror, and the light can realize an incident angle in the range of 70-110 degrees after being adjusted by the first reflecting mirror; the light is emitted from the third window after passing through the nano-particle solution to be measured, is reflected by the second reflecting mirror, and is incident to a profile analyzer; the reference light is input to the second polarization state adjusting mechanism, is input to the third reflecting mirror, is reflected, is input to the nano-particle solution to be measured from the second window, and the reference light and the first scattered light are combined, are input to the third polarization state adjusting mechanism, are input to the fourth reflecting mirror after being reflected, and are input to a signal acquisition and calculation mechanism. The application has high measurement precision, low uncertainty and small systematic deviation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material measurement, in particular to a dynamic light scattering experimental device and method. BACKGROUND

[0002] Nanomaterials have important applications in the fields of biology, chemical industry, energy, etc. due to their unique surface effect, size effect and quantum tunneling effect. Therefore, it is urgent to deeply study the characteristics of nanomaterials and improve the efficiency and quality of preparing nanomaterials. However, the industrialization process of nanomaterials is seriously restricted by the accurate measurement of key physical property parameters such as diffusion coefficient. The diffusion coefficient directly affects the formation efficiency of nanoparticles, the separation purity and the calculation of the hydrodynamic diameter based on the Stokes-Einstein equation. At present, dynamic light scattering (DLS for short) is the core means for measuring the diffusion coefficient of nanoparticles.

[0003] The existing dynamic light scattering device can only measure the diffusion coefficient of a single dispersed spherical nanoparticle system such as a uniform polystyrene solution. For a multi-dispersed nanoparticle system such as a nanoparticle-base fluid mixed system and a complex nanoparticle dispersion system such as a rod-shaped nanoparticle dispersion system, the measurement accuracy is poor due to low signal-to-noise ratio, high concentration sample susceptible to multiple scattering interference, and many parameters to be fitted, especially the correlation function fitting of the multi-dispersed nanoparticle system is complex. In addition, the existing dynamic light scattering device can only measure a fixed angle, resulting in high uncertainty. At the same time, the existing dynamic light scattering device cannot measure the overall refractive index of nanofluid, and directly uses the refractive index of base fluid to replace the overall refractive index of nanofluid, which introduces systematic bias due to refractive index error. SUMMARY

[0004] The embodiment of the present application provides a dynamic light scattering experimental device and method, which can solve the problems of poor measurement accuracy, high uncertainty and refractive index error of the existing dynamic light scattering device.

[0005] In order to achieve the above purpose, the technical scheme of the embodiment of the present application is as follows:

[0006] In a first aspect, the embodiment of the present application provides a dynamic light scattering experimental device, which comprises a laser generating mechanism, a light splitting plate, a first polarization state adjusting mechanism, a first mirror, a rotating mechanism, an experimental body, a second mirror, a profile analyzer, a second polarization state adjusting mechanism, a third mirror, a third polarization state adjusting mechanism, a fourth mirror and a signal acquisition and calculation mechanism.

[0007] The experimental body is columnar, four windows are arranged on the side wall, the four windows are arranged in an equiangular annular array around the central axis of the experimental body, and the inner cavity is used to place a nanoparticle solution to be measured.

[0008] The incident laser generated by the laser generating mechanism is input to the beamsplitter and is divided into probe light and reference light;

[0009] The first mirror is arranged on a rotating mechanism, and the rotating mechanism drives the first mirror to rotate by a preset angle;

[0010] The probe light is input to the first polarization state adjusting mechanism, is adjusted in polarization state, is input to the first mirror, is reflected by the first mirror, is input from the first window at an incident angle value of 70°-110°, is output from the third window on the opposite side after passing through the solution of the nanoparticles to be measured, and the inner wall surface and the outer wall surface of the third window form an angle of 20°-40°;

[0011] The second mirror is arranged at the position of the third window on the experimental body, and the probe light output from the third window is reflected by the second mirror and is input to the profile analyzer;

[0012] The reference light is input to the second polarization state adjusting mechanism, is adjusted in polarization state, is input to the third mirror, is reflected by the third mirror, and is input from the second window to the solution of the nanoparticles to be measured;

[0013] The reference light and the first scattered light output from the fourth window on the opposite side of the second window are combined, are input to the third polarization state adjusting mechanism, are adjusted in polarization state, are input to the fourth mirror, are reflected by the fourth mirror, and are input to the signal acquisition and calculation mechanism.

[0014] In combination with the first aspect, in a possible implementation manner, the dynamic light scattering experiment device is characterized in that the device further comprises a first diaphragm;

[0015] The first diaphragm is arranged on the light path between the experimental body and the third polarization state adjusting mechanism.

[0016] In combination with the first aspect, in a possible implementation manner, the dynamic light scattering experiment device further comprises a fifth mirror, a beam combiner, a sixth mirror, a seventh mirror, and an eighth mirror;

[0017] The probe light is input from the first window at an incident angle value of -160°--170° or 160°-170° after being adjusted in reflection angle by the first mirror, is output from the third window on the opposite side after passing through the solution of the nanoparticles to be measured;

[0018] The reference light after the second polarization state adjustment mechanism is adjusted by the second polarization state adjustment mechanism is reflected after entering the fifth mirror, the second scattered light formed by the first window entering is combined by a beam combiner, and then reflected by a sixth mirror, and then reflected by a seventh mirror, and then reflected by an eighth mirror, and then enters the third polarization state adjustment mechanism, and then enters the third polarization state adjustment mechanism, and then enters the fourth mirror after the fourth mirror is reflected, and then enters the signal acquisition and calculation mechanism.

[0019] In combination with the first aspect, in a possible implementation, the dynamic light particle scattering experimental device further includes a second diaphragm and a third diaphragm.

[0020] The second diaphragm and the third diaphragm are sequentially arranged on the light path between the beam combiner and the sixth mirror.

[0021] In combination with the first aspect, in a possible implementation, the dynamic light particle scattering experimental device further includes a density sheet.

[0022] The density sheet is arranged on the exit light path of the second polarization state adjustment mechanism, and the probe light after the second polarization state adjustment mechanism is adjusted by the second polarization state adjustment mechanism first enters the density sheet and then exits.

[0023] In combination with the first aspect, in a possible implementation, the dynamic light particle scattering experimental device further includes a fourth diaphragm.

[0024] The fourth diaphragm is arranged on the light path between the third polarization state adjustment mechanism and the fourth mirror.

[0025] In combination with the first aspect, in a possible implementation, the signal acquisition and calculation mechanism includes a beam splitter prism, a first photomultiplier tube, a second photomultiplier tube, a high-speed linear digital correlator, and a calculation storage structure.

[0026] The light reflected by the fourth mirror enters the beam splitter prism and is divided into first light and second light.

[0027] The first light enters the first photomultiplier tube.

[0028] The second light enters the second photomultiplier tube.

[0029] The first photomultiplier tube and the second photomultiplier tube are electrically connected to the high-speed linear digital correlator.

[0030] The high-speed linear digital correlator is electrically connected to the calculation storage structure.

[0031] In the second aspect, the embodiment of the present application provides a dynamic light scattering experiment method based on the dynamic light scattering experiment device.

[0032] Injecting the nanometer particle solution to be measured into the inner cavity of the experiment body, and adjusting the temperature and pressure of the inner cavity of the experiment body;

[0033] When the temperature of the inner cavity of the experiment body reaches the preset temperature, generating initial laser light to the light splitting sheet by the laser generating mechanism, and adjusting the height of the probe light and the reference light to make them on the same horizontal plane, adjusting the first, second and third polarization state adjusting mechanisms to make the reference light and the probe light be vertical-horizontal combination or vertical-vertical combination, rotating the first mirror by a preset angle by the rotating mechanism, so that the probe light is incident at an angle of 70°-110° from the first window, and then emitted from the third window on the opposite side after passing through the nanometer particle solution to be measured;

[0034] Adjusting the reference light intensity to the weakest state, adjusting the incident laser light intensity to make the photon number be 5KHz-8KHz, then adjusting the reference light intensity to make the contrast of the scattered light intensity autocorrelation function be 1.0%-1.5%, starting the signal acquisition and calculation mechanism, and measuring the offset distance L MN of the probe light offset through the third window by the profile analyzer, and calculating the refractive index n fluid of the nanometer particle solution to be measured by the geometric optics formula;

[0035] Calculating the modulus q of the scattering vector by the modulus calculation formula, fitting the scattered light intensity autocorrelation function g （2） (τ) by the modulus q of the scattering vector, and obtaining the diffusion coefficient of the nanometer particle solution to be measured under different angles, wherein, in the heterodyne mode, the g （2） (τ) of the spherical nanometer particle solution to be measured is b0+b1exp(-q 2 D T τ), wherein b0 and b1 are constant coefficients, q is the modulus of the scattering vector, D T is the translational diffusion coefficient, and τ is the delay time; the g （2） (τ) of the rod-shaped nanometer particle solution to be measured is b0+b1exp(-q 2 D T τ)+b2exp(- (q 2 D T +D R )τ), wherein b0, b1 and b2 are constant coefficients, q is the modulus of the scattering vector, D T is the translational diffusion coefficient, τ is the delay time, and DR The rotational diffusion coefficient is denoted as .

[0036] Uncertainty analysis was performed on the nanoparticle solution to be tested.

[0037] In conjunction with the second aspect, in one possible implementation, the dynamic light particle scattering experimental method also includes installing a fifth mirror, a beam combiner, a sixth mirror, a seventh mirror, and an eighth mirror, followed by light collimation;

[0038] The rotating mechanism drives the first reflector to rotate by a preset angle so that the detection light enters from the first window at an incident angle of -160° to -170° or 160° to 170°.

[0039] In conjunction with the second aspect, in one possible implementation, the refractive index n of the solution containing the nanoparticles to be measured is calculated. fluid include:

[0040] Adjust the probe light so that it is perpendicular to the second window of the experimental body. Mark the position on the profile analyzer as point M. Rotate the experimental body through the angle rotation mechanism. Mark the position on the profile analyzer as point N, L. MN The offset distance by which the probe light deviates after passing through the third window;

[0041] The refractive index n of the nanoparticle solution under test was calculated using a set of geometric optical relationship formulas. fluid The set of formulas for calculating geometric-optical relationships is as follows:

[0042] ;

[0043] In the formula, n fluid Let n be the refractive index of the nanoparticle solution to be tested, k be the incident angle of the probe light at the inner wall of the third window, and n be the refractive index of the nanoparticle solution to be tested. glass Let α be the refractive index of the third window material, α be the refraction angle of the probe light at the inner wall of the third window, β be the incident angle of the probe light at the outer wall of the third window, and n be the refractive index of the third window material. air Where is the air refractive index, γ is the angle of refraction of the probe light at the outer wall of the third window, and L is the refractive index of air. MN L1 is the offset distance of the probe light after passing through the third window, L2 is the distance between the outer wall of the third window and the profile analyzer, and L1 is the vertical distance between the incident point of the probe light on the inner wall of the third window and the outer wall.

[0044] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0045] The experimental device based on dynamic light scattering provided by the embodiment of the application has a columnar experimental body, four windows are arranged on the side wall, the four windows are arranged in an equiangular annular array around the central axis of the experimental body, and a nanometer particle solution to be measured is placed in the inner cavity. The experimental device allows probe light to enter the first window at an angle of 70°-110°, pass through the nanometer particle solution to be measured, and exit from the third window. Reference light enters the second window, passes through the nanometer particle solution to be measured, and exits from the fourth window, thereby optimizing the light scattering path. The reference light provided by the embodiment of the application is in a heterodyne detection mode, so that a reference light beam of the same source is superimposed on the first scattered light, and then the reference light beam is detected and analyzed. The heterodyne detection scheme can improve the signal-to-noise ratio of the signal, help improve the measurement accuracy of the experiment, shorten the measurement time, and still achieve a relatively optimal measurement effect for a nanometer particle solution with a relatively low concentration. In addition, multiple scattering can be effectively suppressed. When the concentration of the nanometer particle solution increases, multiple scattering increases. The experimental device of the embodiment of the application has an advantage in measuring the diffusion coefficient of a high-concentration sample. Moreover, the autocorrelation function of the scattering light intensity can be simplified, especially for a polydisperse nanometer particle system and a non-spherical nanometer particle system, and the fitting is simplified. The first mirror is arranged on a rotating mechanism, the rotating mechanism can drive the first mirror to rotate by a preset angle, the probe light enters the first mirror after being adjusted by the first polarization state adjusting mechanism, the incident angle value is changed by rotation, the probe light is allowed to be continuously measured at an angle of 70°-110°, a multi-angle data set is obtained, and single-angle deviation is reduced. The rotating mechanism is rotated by a preset angle, so that the experimental device reduces the measurement uncertainty of the diffusion coefficient, is suitable for systems with different particle sizes, enhances the universality of the device, and solves the problem of high uncertainty caused by a fixed measurement angle. The inner wall surface and the outer wall surface of the third window are arranged at an angle of 20°-40°, profile analysis can be used to assist in calculating the refractive index, and systematic deviation is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the description of the embodiments of the application will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0047] Figure 1 The experimental device based on dynamic light scattering provided by the embodiment of the application has a columnar experimental body, four windows are arranged on the side wall, the four windows are arranged in an equiangular annular array around the central axis of the experimental body, and a nanometer particle solution to be measured is placed in the inner cavity. The experimental device allows probe light to enter the first window at an angle of 70°-110°, pass through the nanometer particle solution to be measured, and exit from the third window. Reference light enters the second window, passes through the nanometer particle solution to be measured, and exits from the fourth window, thereby optimizing the light scattering path. The reference light provided by the embodiment of the application is in a heterodyne detection mode, so that a reference light beam of the same source is superimposed on the first scattered light, and then the reference light beam is detected and analyzed. The heterodyne detection scheme can improve the signal-to-noise ratio of the signal, help improve the measurement accuracy of the experiment, shorten the measurement time, and still achieve a relatively optimal measurement effect for a nanometer particle solution with a relatively low concentration. In addition, multiple scattering can be effectively suppressed. When the concentration of the nanometer particle solution increases, multiple scattering increases. The experimental device of the embodiment of the application has an advantage in measuring the diffusion coefficient of a high-concentration sample. Moreover, the autocorrelation function of the scattering light intensity can be simplified, especially for a polydisperse nanometer particle system and a non-spherical nanometer particle system, and the fitting is simplified. The first mirror is arranged on a rotating mechanism, the rotating mechanism can drive the first mirror to rotate by a preset angle, the probe light enters the first mirror after being adjusted by the first polarization state adjusting mechanism, the incident angle value is changed by rotation, the probe light is allowed to be continuously measured at an angle of 70°-110°, a multi-angle data set is obtained, and single-angle deviation is reduced. The rotating mechanism is rotated by a preset angle, so that the experimental device reduces the measurement uncertainty of the diffusion coefficient, is suitable for systems with different particle sizes, enhances the universality of the device, and solves the problem of high uncertainty caused by a fixed measurement angle. The inner wall surface and the outer wall surface of the third window are arranged at an angle of 20°-40°, profile analysis can be used to assist in calculating the refractive index, and systematic deviation is reduced. Figure 1 ;

[0048] Figure 2 The light path diagram of the probe light passing through the third window provided by the embodiment of the application is shown in the figure.

[0049] Figure 3 The experimental device based on dynamic light scattering provided by the embodiment of the application has a columnar experimental body, four windows are arranged on the side wall, the four windows are arranged in an equiangular annular array around the central axis of the experimental body, and a nanometer particle solution to be measured is placed in the inner cavity. The experimental device allows probe light to enter the first window at an angle of 70°-110°, pass through the nanometer particle solution to be measured, and exit from the third window. Reference light enters the second window, passes through the nanometer particle solution to be measured, and exits from the fourth window, thereby optimizing the light scattering path. The reference light provided by the embodiment of the application is in a heterodyne detection mode, so that a reference light beam of the same source is superimposed on the first scattered light, and then the reference light beam is detected and analyzed. The heterodyne detection scheme can improve the signal-to-noise ratio of the signal, help improve the measurement accuracy of the experiment, shorten the measurement time, and still achieve a relatively optimal measurement effect for a nanometer particle solution with a relatively low concentration. In addition, multiple scattering can be effectively suppressed. When the concentration of the nanometer particle solution increases, multiple scattering increases. The experimental device of the embodiment of the application has an advantage in measuring the diffusion coefficient of a high-concentration sample. Moreover, the autocorrelation function of the scattering light intensity can be simplified, especially for a polydisperse nanometer particle system and a non-spherical nanometer particle system, and the fitting is simplified. The first mirror is arranged on a rotating mechanism, the rotating mechanism can drive the first mirror to rotate by a preset angle, the probe light enters the first mirror after being adjusted by the first polarization state adjusting mechanism, the incident angle value is changed by rotation, the probe light is allowed to be continuously measured at an angle of 70°-110°, a multi-angle data set is obtained, and single-angle deviation is reduced. The rotating mechanism is rotated by a preset angle, so that the experimental device reduces the measurement uncertainty of the diffusion coefficient, is suitable for systems with different particle sizes, enhances the universality of the device, and solves the problem of high uncertainty caused by a fixed measurement angle. The inner wall surface and the outer wall surface of the third window are arranged at an angle of 20°-40°, profile analysis can be used to assist in calculating the refractive index, and systematic deviation is reduced.Figure 2 ;

[0050] Figure 4 A structural schematic diagram of an experimental ontology provided for an embodiment of the present application;

[0051] Figure 5 A perspective view of another experimental ontology provided for an embodiment of the present application;

[0052] Figure 6 A top view of the experimental ontology of Figure 5 ;

[0053] Figure 7 A view in the direction of A-A in Figure 6 ;

[0054] Figure 8 A view in the direction of B-B in Figure 6 ;

[0055] Figure 9 A diagram of the diffusion coefficient of polystyrene nanoparticle solution varying with concentration in the heterodyne mode and the homodyne mode provided for an embodiment of the present application;

[0056] Figure 10 A diagram of the light intensity autocorrelation function of scattered light of a rod-shaped nanoparticle solution and its fitting provided for an embodiment of the present application.

[0057] Figure: 1 - laser generating mechanism; 11 - laser; 12 - lens; 2 - light splitting plate; 3 - first polarization state adjusting mechanism; 31 - first 1 / 2 plate; 32 - first polarizing beam splitter prism; 33 - first baffle; 4 - first mirror; 5 - rotating mechanism; 6 - experimental ontology; 61 - first window; 62 - second window; 63 - third window; 64 - fourth window; 65 - second mounting hole; 66 - first platinum resistance; 67 - second platinum resistance; 7 - second mirror; 8 - profile analyzer; 9 - second polarization state adjusting mechanism; 91 - second 1 / 2 plate; 92 - second polarizing beam splitter prism; 93 - second baffle; A - third mirror; B - third polarization state adjusting mechanism; B1 - third 1 / 2 plate; B2 - third polarizing beam splitter prism; B3 - third baffle; C - fourth mirror; D - signal acquisition and calculation mechanism; D1 - polarizing beam splitter prism; D2 - first photomultiplier tube; D3 - second photomultiplier tube; D4 - high-speed linear digital correlator; D5 - calculation storage structure; E - first diaphragm; F - fifth mirror; G - beam combining mirror; H - sixth mirror; I - seventh mirror; J - eighth mirror; K - second diaphragm; L - third diaphragm; M - density plate; N - fourth diaphragm; O - nanoparticle solution to be measured; P - braided silica gel heating wire; Q - constant temperature bath circulating mechanism; R - pressurizing mechanism; θ - incident angle value. DETAILED DESCRIPTION

[0058] Clearly and completely describe the technical solutions in the embodiments of the present application in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0059] In the description of the embodiments of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. The terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In addition, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0060] Please refer to Figure 1 The embodiments of the present application provide a dynamic light particle scattering experimental device based on a dynamic light particle scattering experimental device, which comprises a laser generating mechanism 1, a light splitting piece 2, a first polarization state adjusting mechanism 3, a first mirror 4, a rotating mechanism 5, an experimental body 6, a second mirror 7, a profile analyzer 8, a second polarization state adjusting mechanism 9, a third mirror A, a third polarization state adjusting mechanism B, a fourth mirror C and a signal acquisition and calculation mechanism D.

[0061] The experimental body 6 is columnar, four windows are arranged at the same height on the side wall, the four windows are arranged in an equiangular annular array around the central axis of the experimental body 6, that is, the included angle between adjacent windows is 90°, and the experimental body 6 is placed in the cavity of the experimental body 6.

[0062] The experimental body 6 is made of 316L stainless steel, which has the characteristics of corrosion resistance, etc., and can be a four-prism shape (a radial cross-sectional view of the experimental body 6 is shown in the figure) as shown in Figure 1 , Figure 3 and Figure 4 The experimental body 6 is made of 316L stainless steel, which has the characteristics of corrosion resistance, etc., and can be a four-prism shape (a radial cross-sectional view of the experimental body 6 is shown in the figure) as shown in Figures 5-8The outer surface of the experimental body 6 is wrapped with a woven silica gel heating wire P, or a temperature adjusting structure such as a nickel-copper heating wire (an outer diameter of 3 mm, an electrical resistance of 2 Ω / m, a temperature range of RT~523 K, and a temperature fluctuation degree of less than 10 mK / 15 min) protected by polytetrafluoroethylene and carbon fiber is used to heat the experimental body 6, for temperature control of the inner cavity of the experimental body 6. The second window 62 of the experimental body 6 is provided with a first mounting hole, and a first platinum resistance 66 is inserted into the first mounting hole. The top surface of the experimental body 6 is provided with a second mounting hole 65, and a second platinum resistance 67 is inserted into the second mounting hole 65. The first platinum resistance 66 and the second platinum resistance 67 serve as temperature measurement structures, the first platinum resistance 66 is connected to the heater, for feedback adjustment and control of the temperature, and the second platinum resistance 67 is used for measuring the temperature to prevent temperature deviation, so as to realize experiments of the to-be-measured nanoparticle solution O at different temperatures.

[0063] The temperature adjusting structure and the temperature measurement structure are electrically connected with the signal acquisition and calculation mechanism D, so that the temperature can be automatically set. In the experiment, according to the time and running time saved by the autocorrelation function, the log file of the temperature adjusting structure is automatically read, and the temperature of the measurement working condition is automatically extracted.

[0064] The experimental body 6 is fixed on a height adjusting mechanism and an angle rotating mechanism. The height adjusting mechanism is used to adjust the experimental body 6 to a reasonable height, so that the probe light can pass through the to-be-measured nanoparticle solution O at the best position. The angle rotating mechanism 5 is used to rotate the experimental body 6 by a preset angle.

[0065] The existing structure for containing the to-be-measured nanoparticle solution O is a cuvette, but the cuvette cannot be sealed. As shown in FIG. 1, Figures 6-9 the bottom surface of the columnar experimental body 6 is closed, the inside is hollow, the top surface is open, and four windows are arranged on the side wall. Each window is fixed by a bolt. After the to-be-measured nanoparticle solution O is put into the top surface, the top surface opening is closed by a top plate and a bolt, and the experimental body 6 is sealed as a whole, so that the experimental body 6 can be used for high-pressure experiments.

[0066] The incident laser generated by the laser generating mechanism 1 is input to the light splitting sheet 2 and is divided into probe light (transmitted light) and reference light (reflected light). The laser generating mechanism 1 includes a laser 11 and a lens 12. The light source power of the laser 11 is 300 mW, and the wavelength λ0 is 532 nm. The initial laser emitted by the laser 11 is focused by the lens 12, and the focal point is located near the experimental body 6.

[0067] The first reflecting mirror 4 is arranged on the rotating mechanism 5, and the rotating mechanism 5 drives the first reflecting mirror 4 to rotate by a preset angle. The rotating mechanism 5 can be a high-precision rotating table.

[0068] The probe light is emitted into the first polarization state adjusting mechanism 3, is adjusted in polarization state, is emitted into the first mirror 4, is adjusted in reflection angle, is emitted from the first window 61 at an incident angle value θ of 70°-110°, is emitted from the third window 63 opposite to the first window 61 after passing through the nanometer particle solution O to be measured, wherein the inner wall surface of the third window 63 is at an angle of 20°-40° with the outer wall surface, that is, the inner wall surface of the third window 63 is wedge-shaped. The second mirror 7 is arranged at the position of the third window 63 on the experimental body 6, and the probe light emitted from the third window 63 is reflected by the second mirror 7 and then is incident into the profile analyzer 8. The profile analyzer 8 is used for measuring the light deviation to obtain the refractive index of the nanometer particle solution O to be measured.

[0069] The first polarization state adjusting mechanism 3 comprises a first 1 / 2 glass 31 and a first polarization light splitting prism 32 arranged in sequence along the light emission direction, and the combination can adjust the light intensity of the incident light. The first polarization light splitting prism 32 is provided with a first baffle 33 on the side surface, the first baffle 33 is black, and the protection measures are formed to prevent the laser from being irradiated on the wall surface, glass surface and other surfaces, to avoid the harm caused by the light irradiation to the outside of the test table and the danger to the operator. The reflection angle value adjustment of the first mirror 4 is realized by rotating the first mirror 4 by a preset angle through the rotating mechanism 5. The combination of the first polarization state adjusting mechanism 3, the first mirror 4 and the rotating mechanism 5 is used for adjusting the probe light to a reasonable light intensity and the incident angle value θ, and then the probe light is emitted into the experimental body 6.

[0070] When the probe light is vertically incident from the first window 61, the incident angle is 0°, Figure 1 The incident angle of the probe light is vertically counterclockwise rotation of 20°, which is recorded as +20°, and the incident angle value θ of the probe light after the reflection angle adjustment of the first mirror 4 is 90°+20°=110°. If the incident angle of the probe light is vertically clockwise rotation of 20°, which is recorded as -20°, the incident angle value θ of the probe light after the reflection angle adjustment of the first mirror 4 is 90°-20°=70°. After the reflection angle adjustment of the first mirror 4, the probe light is emitted from the first window 61 at the incident angle value θ of 70°-110°, and the scattering experiment of the nanometer particle solution O to be measured at different angles can be realized.

[0071] For the traditional particle scattering device, when the incident angle is near 90°, the light collimation depends on the angle between the two adjacent planes of the cuvette or the two adjacent windows of the body, which is 90°. However, the angle between the two adjacent planes of the cuvette or the two adjacent windows of the body cannot be guaranteed to be 90° due to the deviation in the processing of the cuvette or the body, and the deviation is difficult to quantify. In the present application, the first mirror 4 is placed on the rotating mechanism 5, and high-precision light collimation can be realized by rotating the first mirror 4.

[0072] The windows are all made of quartz glass. The first window 61, the second window 62 and the fourth window 64 are cylindrical, and the outer wall surface and the inner wall surface are parallel to each other, and have high parallelism. For example, the size is a diameter of 30 mm and a height of 30 mm, and the surface flatness is λ / 10. The inner wall surface and the outer wall surface of the third window 63 form an angle of 20°-40°, so that the refractive index of the to-be-measured nanoparticle solution O can be accurately measured.

[0073] As shown in FIG. 1, the refractive index of the to-be-measured nanoparticle solution O needs to be calculated, and the offset distance L MN of the probe light passing through the third window 63 needs to be measured. MN If the angle between the inner wall surface and the outer wall surface of the third window 63 is too small, the distance L MN will be small, and the measurement accuracy will be poor. If the angle between the inner wall surface and the outer wall surface of the third window 63 is too large, the probe light may not pass through the center point of the experimental body 6 even if it passes through the first window 61, which leads to a failure in the measurement of L MN . The inner wall surface and the outer wall surface of the third window 63 form an angle of 20°-40°, and preferably 30°. When the probe light passes through the first window 61 and the third window 63, the probe light will be offset. In a given transmission distance, the offset difference of the light in the two cases is determined by the camera, so that the refractive index of the to-be-measured nanoparticle solution O can be accurately measured.

[0074] In a dynamic light scattering experiment, the refractive index of the measured medium is needed. A common processing method is to use the refractive index of the base liquid, without considering the influence of the added nanoparticles on the solution. The embodiment of the present application can simultaneously obtain the refractive index of the to-be-measured nanoparticle solution O, and effectively eliminate the influence of the refractive index on the experimental results.

[0075] The reference light is incident into the second polarization state adjusting mechanism 9, is adjusted in polarization state, is reflected by the third mirror A, and is incident into the to-be-measured nanoparticle solution O from the second window 62. The second polarization state adjusting mechanism 9 is used to adjust the reference light to a reasonable light intensity, and includes a second 1 / 2 glass 91 and a second polarization beam splitter prism 92 arranged in sequence along the light emission direction, and the combination can adjust the light intensity of the reference light. The second polarization beam splitter prism 92 is provided with a second baffle 93 on the side surface, the second baffle 93 is black, and a protection measure is formed to prevent the laser from being irradiated on the wall surface, glass surface and the like, so as to avoid the light irradiation to the outside of the test table and bring danger to the operator.

[0076] The reference light and the first scattered light emitted from the fourth window 64 opposite to the second window 62 are combined and then enter the third polarization state adjusting mechanism B, are adjusted in polarization state, are reflected by the fourth mirror C, enter the signal acquisition and calculation mechanism D, the reference light and the first scattered light are superposed and are detected by the signal acquisition and calculation mechanism D, the signal can be amplified, and the measurement precision is improved. The device of the embodiment of the application realizes heterodyne mode detection of dynamic light particle scattering due to the arrangement of the reference light, the scattered light intensity autocorrelation function only needs three parameters, is simplified, is convenient for calculation, and is suitable for measurement of diffusion coefficients of multi-element dispersed nanoparticle systems.

[0077] The third polarization state adjusting mechanism B comprises a third 1 / 2 glass B1 and a third polarization beam splitter prism B2 arranged in sequence along the light emission direction.

[0078] The experimental device provided by the embodiment of the application has vertical polarization (V) of the incident initial laser, the polarization of the initial laser has no influence on the experimental measurement for spherical particle solution, and the first polarization state adjusting mechanism 3 is arranged between the detection light and the experimental body 6 for rod-shaped nanoparticles, the second polarization state adjusting mechanism 9 is arranged between the reference light and the experimental body 6, and the third polarization state adjusting mechanism B is arranged between the combined light of the first scattered light and the reference light and the signal acquisition and calculation mechanism D, the first polarization state adjusting mechanism 3, the second polarization state adjusting mechanism 9 and the third polarization state adjusting mechanism B can adjust the polarization state of the light, can obtain the scattered light intensity autocorrelation function under vertical polarization, vertical polarization combination (VV) and vertical polarization, horizontal polarization (VH) combination, and are beneficial to measurement of rod-shaped nanoparticle solution.

[0079] In the light path adjustment process, when the incident angle value θ is in the range of 70-110°, the probe light and the reference light are at the same level, and the light collimation is relatively easy. First, adjust the first mirror 4 on the rotating mechanism 5 so that the reflected probe light is perpendicular to the first window 61 of the experimental body 6. At this time, the reflected light spot after the probe light is reflected by the first window 61 of the experimental body 6 should be observed at the first 1 / 2 glass 31. Second, adjust the third mirror A so that the reflected reference light is perpendicular to the second window 62 of the experimental body 6, and is sequentially reflected by the third polarization state adjustment mechanism B and the fourth mirror C and is detected by the signal acquisition and calculation mechanism D. At this time, the reflected light spot should also be observed at the second 1 / 2 glass 91. After the two steps, the light path adjustment is completed. Since the angle between the windows of the experimental body 6 is 90°, the incident angle value θ at this time is 90°. Due to the size limitation of the windows of the experimental body 6 and the length limitation of the guide rail, it can be ensured that the probe light of ±20° can pass through the experimental body 6. Therefore, at this time, the scattering experiment of the to-be-measured nanoparticle solution O in the range of 70-110° can be realized.

[0080] The experimental device based on the dynamic light scattering experiment device provided by the embodiment of the application has a columnar experimental body 6, four windows are arranged on the side wall, the four windows are arranged in an equiangular annular array around the central axis of the experimental body 6, and a nanometer particle solution O is placed in the inner cavity. The experimental device allows probe light to enter the first window 61 at an angle of 70°-110°, pass through the nanometer particle solution O, and exit from the third window 63. Reference light enters the second window 62, passes through the nanometer particle solution O, and exits from the fourth window 64. The light scattering path is optimized. The reference light provided in the embodiment of the application is in a heterodyne detection mode, so that a reference light beam of the same source is superimposed on the first scattered light, and then the first scattered light is detected and analyzed. The heterodyne detection scheme can improve the signal-to-noise ratio of the signal, help to improve the measurement accuracy of the experiment and shorten the measurement time, and can still achieve a better measurement effect for a nanometer particle solution with a relatively low concentration. In addition, multiple scattering can be effectively suppressed. When the concentration of the nanometer particle solution increases, multiple scattering increases. The experimental device of the embodiment of the application has an advantage in measuring the diffusion coefficient of a high-concentration sample. Moreover, the autocorrelation function of the scattering light intensity can be simplified, especially for a polydisperse nanometer particle system and a non-spherical nanometer particle system, and the fitting is simplified. The first mirror 4 is arranged on the rotating mechanism 5, the rotating mechanism 5 can drive the first mirror 4 to rotate by a preset angle, the probe light enters the first mirror 4 after being adjusted by the first polarization state adjusting mechanism 3, the incident angle value θ is changed by rotation, the probe light is allowed to be continuously measured at an angle of 70°-110°, a multi-angle data set is obtained, and single-angle deviation is reduced. The rotating mechanism 5 is rotated by a preset angle, so that the experimental device reduces the measurement uncertainty of the diffusion coefficient, is suitable for systems with different particle sizes, enhances the universality of the device, and solves the problem of high uncertainty caused by a fixed measurement angle. The inner wall surface and the outer wall surface of the third window 63 are arranged at an angle of 20°-40°, which can assist in calculating the refractive index in combination with the contour analyzer 8, and reduces systematic deviation.

[0081] The first polarization state adjusting mechanism 3 adjusts the probe light, the second polarization state adjusting mechanism 9 adjusts the reference light, and the third polarization state adjusting mechanism B adjusts the combined light of the first scattered light and the reference light, so as to flexibly control the polarization state of the light beam and reduce stray light and noise. The first scattered light emitted from the fourth window 64 passes through the third polarization state adjusting mechanism B and the fourth mirror C, and then enters the signal acquisition and calculation mechanism D, so as to realize accurate signal capture and real-time analysis. The cylindrical experimental body 6 and the four windows reduce the non-target scattering in the optical path, and in combination with the polarization state adjustment, the background noise of the multiple scattering interference is effectively suppressed. The signal acquisition and calculation mechanism D provides high-precision data acquisition and calculation, is suitable for correlation function fitting of a multi-element / complex nanoparticle system, reduces the fitting complexity, and has high measurement accuracy for a multi-element dispersed nanoparticle system and a complex nanoparticle dispersion system. The probe light is incident at an incident angle value θ of 70° to 110°, and is emitted from the third window 63 at an angle of 20° to 40° between the inner wall surface and the outer wall surface. This non-perpendicular incidence design reduces the path length of the light in the solution, thereby reducing the probability of multiple scattering. The probe light is reflected to the profile analyzer 8 through the second mirror 7, the first scattered light generated by the reference light passes through an independent optical path, enters the signal acquisition and calculation mechanism D through the third polarization state adjusting mechanism B and the fourth mirror C, and the separation design avoids signal cross interference. The profile analyzer 8 is used to analyze the spatial distribution of the probe light, the incident angle value θ is 70° to 110°, and the third window 63 is designed to have an angle of 20° to 40° between the inner wall surface and the outer wall surface, so as to physically limit the optical path and reduce the multiple reflection events under high concentration.

[0082] As shown in Figure 1 , the dynamic light particle scattering experimental device further comprises a first light barrier E. The first light barrier E is arranged on the optical path between the experimental body 6 and the third polarization state adjusting mechanism B. The arrangement of the first light barrier E can filter out the stray noise of the combined light emitted from the fourth window 64, especially the background light generated by the turbulent flow of the nanoparticle solution O to be measured under high pressure.

[0083] Referring to Figure 3 , the dynamic light particle scattering experimental device further comprises a fifth mirror F, a beam combiner G, a sixth mirror H, a seventh mirror I, and an eighth mirror J.

[0084] When the probe light is vertically incident, the incident angle is 180°, Figure 3The incident angle of the probe light is vertically counterclockwise rotated by 20°, denoted as +20°, and the incident angle value θ of the probe light after being reflected by the first mirror 4 is 180°+20°=200°=-160°. If the incident angle of the probe light is vertically clockwise rotated by 20°, denoted as -20°, the incident angle value θ of the probe light after being reflected by the first mirror 4 is 180°-20°=160°. Considering the shielding of the beam combiner G, the incident angle of the probe light is 10°~20° and -20°~-10°, and therefore, the scattering experiment of the to-be-measured nanoparticle solution O can be implemented at different incident angle values θ of -160°~-170° or 160°~170°, further widening the measurable incident angle value θ.

[0085] The reference light after being adjusted in the second polarization state by the second polarization state adjustment mechanism 9 is reflected by the fifth mirror F, and the second scattered light formed by the first window 61 is combined by the beam combiner G, and then reflected by the sixth mirror H and the seventh mirror I, and then reflected by the eighth mirror J, and then enters the third polarization state adjustment mechanism B, and then enters the fourth mirror C after being adjusted in the polarization state by the third polarization state adjustment mechanism B, and then enters the signal acquisition calculation mechanism D. The beam combiner G solves the problem of coincidence of the reference light and the second scattered light.

[0086] When the incident angle value θ ranges from -160° to -170° or from 160° to 170°, the first mirror 4 of the rotation adjustment mechanism 5 is adjusted so that the reflected probe light is perpendicular to the first window 61 of the experimental body 6, and at this time, the reflected light spot of the probe light reflected by the first window 61 of the experimental body 6 should be observed at the first 1 / 2 glass 31. Two points can determine a straight line.

[0087] In practice, the existing device measures the diffusion coefficient of the to-be-measured nanoparticle solution O at a certain measurement angle multiple times and calculates the average value, which may underestimate the measurement reliability and have a large deviation. The experimental device of the embodiment of the present application can realize the switching of multiple incident angle values θ of 70°~110°, -160°~-170° or 160°~170°, has a wider measurement angle, has a smaller deviation when calculating the average value of the diffusion coefficients of multiple incident angle values θ, and can measure the colored nanoparticle solution by adjusting the fifth mirror F, the beam combiner G, the sixth mirror H, the seventh mirror I, the eighth mirror J and the incident angle value θ.

[0088] Further, the angles of the general fifth mirror F, the beam combiner G, the sixth mirror H, the seventh mirror I and the eighth mirror J are not changed, and only mounting and dismounting is needed, the bases thereof are made of magnetic material, and the bases are arranged on the magnetic bases, so that the positions thereof can be quickly restored and dismounted, and the experimental light paths in the vertical scattering mode and the reflection mode can be quickly built. After the fifth mirror F is mounted, the reference light no longer passes through the third mirror A. After the fifth mirror F is dismounted, the reference light passes through the third mirror A again.

[0089] The experimental device provided by the embodiment of the present application is a dynamic light particle scattering experimental device based on heterodyne mode detection, wherein in the experimental process, the reference light is shielded (i.e. a light shielding object is placed at the spectroscope 2 and the first polarization state adjusting mechanism 3), and the homodyne mode detection scheme can also be realized, that is, only the detection light is detected and subjected to relevant operation.

[0090] As shown in Figure 3 , the dynamic light particle scattering experimental device comprises a second diaphragm K and a third diaphragm L. The second diaphragm K and the third diaphragm L are sequentially arranged on the light path between the beam combiner G and the sixth mirror H. The aperture φ of the diaphragm is 1 mm. When the reference light is collimated, the second diaphragm K and the third diaphragm L can first assist in adjusting the detection light to vertically enter the first window 61 of the experimental body 6, and secondly assist in determining the position of the reference light. Specifically, the reference light passes through the aperture of the second diaphragm K and the third diaphragm L after being adjusted by the beam combiner G and the eighth mirror J, and at this time, it can be ensured that the reference light and the second scattered light are completely in the same position.

[0091] As shown in Figure 1 and Figure 3 , the dynamic light particle scattering experimental device further comprises a density sheet M. The density sheet M is arranged on the emergent light path of the second polarization state adjusting mechanism 9, and the detection light adjusted in polarization state by the second polarization state adjusting mechanism 9 is first incident into the density sheet M and then emitted. In the measurement of high-concentration nanoparticles, the light intensity is further attenuated by the density sheet M, dynamic light intensity compensation is realized, and saturation of the signal acquisition and calculation mechanism D is prevented. The output fluctuation caused by direct adjustment of the laser power can also be avoided, the stability of the light source is ensured, and the cross-correlation measurement accuracy is ensured.

[0092] As shown in Figure 1 and Figure 3 , the dynamic light particle scattering experimental device further comprises a fourth diaphragm N. The fourth diaphragm N is arranged on the light path between the third polarization state adjusting mechanism B and the fourth mirror C, so as to intercept the stray reflection light generated by the polarization adjustment of the third polarization state adjusting mechanism B, and realize the ultimate filtering of the signal end. The fourth diaphragm N, the first diaphragm E, the second diaphragm K and the third diaphragm L form a three-level spatial filtering chain, so as to improve the signal-to-noise ratio in a high-pressure environment.

[0093] Continuing to refer toFigure 1 and Figure 3 As shown in the figure, the signal acquisition calculation mechanism D includes a beam splitter prism D1, a first photomultiplier D2, a second photomultiplier D3, a high-speed linear digital correlator D4, and a calculation storage structure D5. The light reflected by the fourth mirror C enters the beam splitter prism D1 and is divided into a first light and a second light. The first light enters the first photomultiplier D2. The second light enters the second photomultiplier D3. The first photomultiplier D2 and the second photomultiplier D3 are electrically connected with the high-speed linear digital correlator D4. The high-speed linear digital correlator D4 is electrically connected with the calculation storage structure D5. The calculation storage structure D5 can be a computer.

[0094] In practice, the profile analyzer 8 measures the offset distance L of the probe light from the third window 63 MN The refractive index of the solution O of the nanoparticles to be measured is obtained. After the scattered light and the reference light are simultaneously split by the beam splitter prism D1, the scattered light and the reference light enter the first photomultiplier D2 and the second photomultiplier D3 respectively and are detected and converted into electrical signals. By setting the first photomultiplier D2 and the second photomultiplier D3, defects can be suppressed, common-mode noise can be eliminated differentially, and higher measurement accuracy can be achieved. The high-speed linear digital correlator D4 obtains the scattered light intensity autocorrelation function for cross-correlation operation. The calculation storage structure D5 analyzes the experimental data. The experimental device provided by the embodiment of the application is particularly suitable for measuring the diffusion coefficient of nanoparticles in a wide temperature range and a wide pressure range in a polydisperse and complex system.

[0095] The device is placed on a high-precision air floatation vibration isolation platform or a high-precision optical vibration isolation platform, which can effectively isolate the influence of external disturbances on experimental measurement, avoid or weaken the influence of environmental disturbances on experiments, and avoid the influence of external factors such as vibration on experimental measurement, especially for systems with a large relaxation time. Compared with the traditional relaxation mode of molecular fluid, the frequency of nanoparticle motion in nanofluid is closer to the frequency of macro-environmental influence. The experimental device of the embodiment of the application is built on a high-precision air cushion optical vibration isolation platform, which can effectively prevent environmental disturbances from affecting the results of dynamic light particle scattering. The experimental device has high reliability for testing the diffusion coefficient of a nanoparticle system, and the mass concentration range of the nanoparticle is 10 -7 ~10 -1 The maximum pressure of the experiment is 40 MPa, and the temperature is 30℃-250℃. The temperature range can be further expanded.

[0096] The embodiment of the application provides a dynamic light particle scattering experimental method based on the dynamic light particle scattering experimental device.

[0097] Step 1: clean and dry the experimental body to keep the experimental body 6 clean and tidy, and avoid affecting the experimental results. Inject the test nanoparticle solution O into the inner cavity of the experimental body 6, and adjust the temperature and pressure of the inner cavity of the experimental body 6, wherein the temperature adjustment includes heating the experimental body 6 by the temperature adjusting structure wrapped on the outer surface of the experimental body 6, and measuring and feedback controlling the temperature by the first platinum resistance 66 and the second platinum resistance 67, the temperature range is 30°C~250°C. The pressure adjustment includes that when the experimental body 6 is in normal pressure, the injection height of the test nanoparticle solution O is greater than 1 / 2 times the height of the window, and when the experimental body 6 is in high pressure, the test nanoparticle solution O fills the inner cavity of the experimental body 6, and the maximum pressure can reach 40MPa. When the pressure in the inner cavity of the experimental body 6 changes, the material in the experimental body 6 will be compressed. If the test nanoparticle solution O does not fill the inner cavity of the experimental body 6, when the pressure is increased, the test nanoparticle solution O will be squeezed to other places, resulting in failure of pressure increase. The test nanoparticle solution O fills the inner cavity of the experimental body 6, which can ensure effective pressure transmission and avoid liquid compression leading to pressure out of control. In practice, as shown in Figure 4 the pressure mechanism R is used to pressurize the experimental body 6.

[0098] The preparation process of the test nanoparticle solution O is as follows: after the prepared initial nanoparticle solution is filtered through a 0.2μm~0.45μm filter, it is dispersed for 10min~15min by an ultrasonic vibrator, and the water bath temperature of the ultrasonic vibrator is kept below 5°C to obtain the test nanoparticle solution O, so that the diameter of the test nanoparticle solution O is not too large, and is uniformly dispersed within a suitable range.

[0099] Step 2: The temperature of the inner cavity of the experimental body 6 is adjusted to the preset temperature, and the initial laser is generated by the laser generating mechanism 1 to the light splitting sheet 2 to divide the initial laser into the probe light and the reference light. The height of the probe light and the reference light is adjusted to make them in the same horizontal plane, and the light collimation is performed (the specific process of the light collimation is as follows: first, the first mirror 4 on the rotating mechanism 5 is adjusted so that the probe light reflected by the first mirror 4 is perpendicular to the first window 61 of the experimental body 6. At this time, the reflected light spot of the probe light after being reflected by the first window 61 of the experimental body 6 should be observed at the first 1 / 2 glass sheet 31. Secondly, the third mirror A is adjusted so that the reference light reflected by the third mirror A is perpendicular to the second window 62 of the experimental body 6 and is sequentially incident into the third polarization state adjusting mechanism B and the fourth mirror C and is detected by the signal acquisition and calculation mechanism D. At this time, the reflected light spot should also be observed at the second 1 / 2 glass sheet 91. The reference light passes through the second window 62 and the fourth window 64, is incident into the signal acquisition and calculation mechanism D through the first light diaphragm E, the third polarization state adjusting mechanism B and the fifth mirror F, and the probe light path adjustment of the probe scheme with the incident angle value θ of 90° is realized), the first polarization state adjusting mechanism 3, the second polarization state adjusting mechanism 9 and the third polarization state adjusting mechanism B are adjusted so that the reference light and the probe light are in the vertical, horizontal combination or the vertical, vertical combination, the first mirror 4 is rotated by a preset angle by the rotating mechanism 5, so that the probe light is incident from the first window 61 at the incident angle value θ of 70°~110°, passes through the to-be-measured nanoparticle solution O and is emitted from the third window 63 on the opposite side.

[0100] As shown in Figure 3 , step 2 further includes installing the fifth mirror F, the beam combiner G, the sixth mirror H, the seventh mirror I and the eighth mirror J, and then performing the light collimation.

[0101] The first mirror 4 is rotated by a preset angle by the rotating mechanism 5, so that the probe light is incident from the first window 61 at the incident angle value θ of -160°~-170° or 160°~170°.

[0102] Step 3: The reference light intensity is adjusted to the weakest state to ensure the safety of the first photomultiplier D2 and the second photomultiplier D3. The incident laser intensity is adjusted so that the photon number is in the range of 5KHz~8KHz (for high-concentration samples or colored samples, the initial laser intensity should be appropriately reduced to avoid the heating effect). Then, the reference light intensity is adjusted so that the contrast of the scattered light intensity autocorrelation function is in the range of 1.0%~1.5%, to ensure the heterodyne detection mode. The signal acquisition and calculation mechanism D is started, and the shift distance probe light L MN of the probe light after the shift of the third window 63 is measured by the profile analyzer 8, and the refractive index N fluid of the to-be-measured nanoparticle solution O is calculated by combining the geometric optics formula. Generally, when the incident angle is 90°, the shift distance probe light LMN , the O refractive index of the to-be-measured nanoparticle solution N is calculated in combination with geometric optics formulas fluid , which can make the calculation simple and convenient.

[0103] The O refractive index of the to-be-measured nanoparticle solution N is calculated fluid , and the O refractive index of the to-be-measured nanoparticle solution N is calculated in combination with geometric optics formulas

[0104] As shown in Figure 2 , the detection light is adjusted to be perpendicular to the second window 62 of the experimental body 6, at this time, the detection light is not deviated, and the position mark on the profile analyzer 8 is point M. The experimental body 6 is rotated by the angle rotating mechanism. Since the inner wall surface and the outer wall surface of the third window 63 are at an angle of 20°~40°, at this time, the detection light is deviated after passing through the third window 63, and the position mark on the profile analyzer 8 is point N. L MN is the deviation distance of the detection light after passing through the third window 63.

[0105] Continuing to refer to Figure 2 , the O refractive index of the to-be-measured nanoparticle solution N is calculated according to a geometric optics relationship calculation formula group fluid , wherein the geometric optics relationship calculation formula group is:

[0106] .

[0107] In the formula, N fluid is the O refractive index of the to-be-measured nanoparticle solution, k is the incident angle of the detection light at the inner wall surface of the third window 63, N glass is the refractive index of the material of the third window 63, in the embodiment of the application, the third window 63 is made of quartz glass, N glass =1.461, α is the refraction angle of the detection light at the inner wall surface of the third window 63, β is the incident angle of the detection light at the outer wall surface of the third window 63, N air is the refractive index of air, γ is the refraction angle of the detection light at the outer wall surface of the third window 63, L MN is the deviation distance of the detection light after passing through the third window 63, and L2 is the distance between the outer wall surface of the third window 63 and the profile analyzer 8, in the embodiment of the application, L2=1m, and L1 is the vertical distance of the detection light at the inner wall surface incident point and the outer wall surface of the third window 63, in the embodiment of the application, L1=24mm.

[0108] Step 4: the modulus q of the scattering vector is calculated by a modulus calculation formula, and the scattering light intensity autocorrelation function g （2） (τ) is fitted by the modulus q of the scattering vector, so as to obtain the diffusion coefficient of the to-be-measured nanoparticle solution O motion at different angles (when the to-be-measured nanoparticle solution O is spherical, the diffusion coefficient is the translational diffusion coefficient D T ; when the to-be-measured nanoparticle solution O is rod-shaped, the diffusion coefficient is the translational diffusion coefficient DT and the rotational diffusion coefficient D R ), wherein, in the heterodyne mode, g （2） (τ) = b0 + b1exp(-q 2 D T τ) for the spherical solution of the nano-particles to be measured O, and g T (τ) = b0 + b1exp(-q （2） D 2 τ) + b2exp(- (q T D 2 + D T ) τ) for the rod-like solution of the nano-particles to be measured O, wherein b0, b1 and b2 are constant coefficients, q is the modulus of the scattering vector, D R is the translational diffusion coefficient, τ is the delay time, and D T is the rotational diffusion coefficient. R

[0109] wherein the modulus calculation formula is: q≌ sin (arcsin ), wherein q is the modulus of the scattering vector, n fluid is the refractive index of the solution of the nano-particles to be measured O, λ is the wavelength of the probe light, and θ is the incident angle value.

[0110] The fitting of the scattered light intensity autocorrelation function g （2） (τ) also includes multi-exponential fitting for the relaxation time τ: g （2） (τ) = b0 + b1exp(-τ / τ C1 ) + b2exp(-τ / τ C2 ), wherein b0, b1 and b2 are constant coefficients, τ is the relaxation time, τ C1 is the relaxation time 1, and τ C2 is the relaxation time 2.

[0111] The hydrodynamic model verification is performed on different relaxation times of the solution of the nano-particles to be measured O, i.e., whether the square of the modulus of the scattering vector q 2 and the reciprocal of the relaxation time τ -1 satisfy the hydrodynamic model, for the translational diffusion coefficient, q 2 and τ -1 are in a linear relationship through the origin, and the slope is the translational diffusion coefficient D T , and for the rotational diffusion coefficient, q 2 and τ -1 are in a linear relationship, and the Y-axis intercept is the rotational diffusion coefficient D R .

[0112] ​Firstly, in the dynamic light scattering theory, the control equation is derived from the N-S equation, and the motion of the measured nanoparticles should satisfy the fluid mechanics model, that is, the square of the scattering vector module q 2 and the reciprocal of the relaxation time τ -1 need to satisfy the linear equation, therefore, experiments need to be conducted in a large scattering angle range to verify whether the fluid mechanics model is satisfied, and the existing device mostly adopts a reflection type detection scheme, that is, the incident angle value θ is near 160°, and it is unable to determine whether the measurement result satisfies the fluid mechanics model. Taking a water solution at normal temperature as an example, the refractive index is 1.3337, the incident laser wavelength is 532 nm, and when the incident angle is 160°-170°, the range of the square of the scattering vector module q 2 is (9.56-9.88) x 10 14 m -2 , and the change value is only 3.3%. The incident angle value θ range of the embodiment of the present application is 70°-170°, the range of the square of the scattering vector module q 2 is 3.69-9.88 x 10 14 m -2 , and the change value increases to 268%.

[0113] Step 5: Uncertainty analysis is performed on the measured nanoparticle solution O, and the standard deviation of the diffusion coefficient at different angles in the range of 70°-170° is calculated as the uncertainty for the ordinary measured nanoparticle solution O. Generally, the standard deviation of the spherical measured nanoparticle solution O needs to be controlled within 3%-5%; the standard deviation of the rod-shaped measured nanoparticle solution O, D T needs to be controlled within 3%-5%, and the standard deviation of D R is ≤10%. For high-concentration or opaque samples, when the incident angle value θ is 160°-170°, the uncertainty is calculated through the error transfer formula D P = 1 / (q 2 τ P ), wherein q is the module of the scattering vector, and τ P is the relaxation time of the measured nanoparticles. If the concentration of the studied nanofluid particles is low, the fluid mechanics diameter and the aspect ratio of the nanoparticles can be obtained according to the Stocks-Einstein relationship.

[0114] It is judged whether the uncertainty meets the requirements, if yes, the experimental measurement result can be used as the final result, otherwise, the experiments with large deviations need to be analyzed and repeated until the re-calculated diffusion coefficient meets the requirements.

[0115] The temperature in the inner cavity of the experiment body 6 is changed, and steps 1-4 are repeated to conduct a multi-temperature zone experiment.

[0116] Here, the diffusion coefficients of polystyrene sphere (PSNP) nanoparticle solution and gold nanorod (AuNP) nanoparticle solution at room temperature are measured by using the above-mentioned dynamic light scattering experimental device and method based on one kind, and the comparison of the heterodyne mode and the homodyne mode is shown in Table 1.

[0117] Table 1

[0118]

[0119] From Table 1 and Figure 9 it can be known that for the spherical nanoparticle solution, the deviation of the diffusion coefficient measured by the homodyne mode is much larger than that measured by the heterodyne mode. Figure 9 The middle prismatic signal is the homodyne mode, the circular signal is the heterodyne mode, and the tolerance column represents the measured deviation. From Figure 9 it can be known that the deviation of the homodyne mode is larger than that of the heterodyne mode. Generally, with the decrease of the concentration, the diffusion coefficient first decreases and then shows a constant trend, and the concentration is a constant when the concentration is zero. However, the rhombus decreases with the decrease of the concentration, which does not conform to the physical law, so it is impossible to measure the accurate value at low concentration. The experimental device and method of the embodiment of the application can measure the diffusion coefficient of the rod-shaped nanoparticle solution.

[0120] From Figure 10 it can be seen that under the same incident power, the signal-to-noise ratio of the signal in the heterodyne mode is much higher than that in the homodyne mode, so under the same incident power, the accuracy of the obtained experimental results is higher, and for some high-concentration or colored samples, lower incident power can be used to effectively avoid the heating effect. At the same time, it can be seen that in the homodyne mode, the signal contrast is about 0.08, which is usually not 1, that is, theoretically, the homodyne condition cannot be met, and the deviation of the relaxation time obtained by the homodyne mode from the relaxation time in the heterodyne mode is 22%, that is, the deviation of the translational diffusion coefficient D T is up to 22%.

[0121] In summary, the experimental device of the embodiment of the application has strong expandability, and can measure the diffusion coefficient of the nanofluid in a large range with higher reliability. The maximum pressure range of the experimental body 6 can reach 40 MPa, and the diffusion behavior of the nanoparticles under different pressures can be studied. The device of the application adopts an electric heating mode, and the temperature range is room temperature to 250 DEG C. In addition, the experimental device of the embodiment of the application increases a constant temperature bath circulating mechanism Q (as shown in Figure 4 , a bath pool is arranged outside the experimental body 6, and a cooling copper pipe is arranged in the bath pool), and the temperature can be expanded to -30 DEG C. The experimental device of the embodiment of the application can measure the diffusion coefficient of the nanoparticles in a high-pressure wide temperature range, and is especially suitable for measuring the diffusion coefficient of a complex nanoparticle dispersion system such as a multi-element and a rod-shaped nanoparticle, and the measurement result is accurate and the measurement range is wide.

[0122] The various embodiments in the specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments.

[0123] The above examples are only used to illustrate the technical solutions of the present application, and are not limited to the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A dynamic light scattering based experimental setup, comprising: The laser generating mechanism, the light splitting piece, the first polarization state adjusting mechanism, the first mirror, the rotating mechanism, the experimental body, the second mirror, the profile analyzer, the second polarization state adjusting mechanism, the third mirror, the third polarization state adjusting mechanism, the fourth mirror and the signal acquisition calculating mechanism are arranged in the experimental device. The experimental body is columnar, four windows are arranged on the side wall, the four windows are arranged in an equiangular annular array around the central axis of the experimental body, and the inner cavity is used for placing a solution of nanoparticles to be measured. The incident laser generated by the laser generating mechanism is input to the light splitting piece and is divided into probe light and reference light. The first mirror is arranged on the rotating mechanism, and the rotating mechanism drives the first mirror to rotate by a preset angle. The probe light is input to the first polarization state adjusting mechanism, is adjusted in polarization state, is input to the first mirror, is reflected by the first mirror, is input from the first window at an incident angle of 70°-110° after the angle is adjusted, is input from the third window on the opposite side after passing through the solution of nanoparticles to be measured, and the inner wall surface of the third window forms an angle of 20°-40° with the outer wall surface. The second mirror is arranged at the position of the third window of the experimental body, the probe light emitted from the third window is reflected by the second mirror and is input to the profile analyzer. The reference light is input to the second polarization state adjusting mechanism, is adjusted in polarization state, is input to the third mirror, is reflected by the third mirror, and is input to the solution of nanoparticles to be measured from the second window. The reference light and the first scattered light emitted from the fourth window on the opposite side of the second window are combined, are input to the third polarization state adjusting mechanism after being adjusted in polarization state, are input to the fourth mirror after being input to the third polarization state adjusting mechanism, are reflected by the fourth mirror, and are input to the signal acquisition calculating mechanism.

2. The dynamic light scattering based particle sizing instrument of claim 1, wherein, The first diaphragm is further arranged. The first diaphragm is arranged on the light path between the experimental body and the third polarization state adjusting mechanism.

3. The dynamic light scattering based particle sizing instrument of claim 1, wherein, The fifth mirror, the beam combiner, the sixth mirror, the seventh mirror and the eighth mirror are further arranged. The probe light is input from the first window at an incident angle of -160°--170° or 160°-170° after the angle is adjusted by the first mirror, is input from the third window on the opposite side after passing through the solution of nanoparticles to be measured, and the inner wall surface of the third window forms an angle of 20°-40° with the outer wall surface. The reference light adjusted in polarization state from the second polarization state adjusting mechanism is reflected by the fifth mirror after being input to the fifth mirror, is combined with the second scattered light formed by the input of the first window through the beam combiner, is reflected by the sixth mirror, is reflected by the seventh mirror, is reflected by the eighth mirror after passing through the eighth mirror, is input to the third polarization state adjusting mechanism, is input to the fourth mirror after being adjusted in polarization state by the third polarization state adjusting mechanism, and is input to the signal acquisition calculating mechanism.

4. The dynamic light scattering based particle sizing instrument of claim 3, wherein, The second diaphragm and the third diaphragm are further arranged. The second diaphragm and the third diaphragm are arranged on the light path between the beam combiner and the sixth mirror in sequence.

5. The apparatus according to any one of claims 1 to 4, wherein The density piece is further arranged. The density piece is arranged on the light path of the second polarization state adjusting mechanism, and the probe light adjusted in polarization state from the second polarization state adjusting mechanism is input to the density piece and is output.

6. The apparatus according to any one of claims 1 to 4, wherein The fourth diaphragm is further arranged. The fourth diaphragm is arranged on the light path between the third polarization state adjusting mechanism and the fourth mirror.

7. The apparatus according to any one of claims 1 to 4, wherein The signal acquisition calculation mechanism comprises a beam splitter prism, a first photomultiplier tube, a second photomultiplier tube, a high-speed linear digital correlator and a calculation storage structure. The light reflected by the fourth mirror enters the beam splitter prism and is divided into first light and second light. The first light enters the first photomultiplier tube. The second light enters the second photomultiplier tube. The first photomultiplier tube and the second photomultiplier tube are electrically connected to the high-speed linear digital correlator. The high-speed linear digital correlator is electrically connected to the calculation storage structure.

8. A method for dynamic light scattering experiment based on, The dynamic light scattering experimental device based on any one of claims 1-7, comprising: Injecting the solution of the nano-particles to be measured into the inner cavity of the experimental body, and adjusting the temperature and pressure of the inner cavity of the experimental body; After the temperature of the inner cavity of the experimental body reaches the preset temperature, the initial laser is generated by the laser generating mechanism to the beam splitter and is divided into probe light and reference light, the height of the probe light and the reference light is adjusted so that they are on the same horizontal plane, the light is collimated, the first polarization state adjusting mechanism, the second polarization state adjusting mechanism and the third polarization state adjusting mechanism are adjusted so that the reference light and the probe light are vertically and horizontally combined or vertically and vertically combined, the first mirror is rotated by a preset angle by the rotating mechanism so that the probe light enters from the first window at an incident angle of 70°-110°, and after passing through the solution of the nano-particles to be measured, it exits from the third window on the opposite side. The reference light intensity is adjusted to the weakest state, the incident laser intensity is adjusted to make the photon number at 5KHz~8KHz, then the reference light intensity is adjusted to make the contrast of the scattered light intensity autocorrelation function at 1.0%~1.5%, the signal acquisition calculator is started, and the shift distance L of the probe light through the third window is measured by the profilometer MN , and the refractive index n of the to-be-measured nanoparticle solution is calculated by combining the geometric optical formula fluid ​ The modulus q of the scattering vector is calculated by a modulus calculation formula, and the scattering light intensity autocorrelation function g is fitted by the modulus q of the scattering vector （2） (τ) is obtained, wherein, in the heterodyne mode, the g （2） (τ) of the spherical solution of the measured nanoparticles is 2 D T (τ) = b0+b1exp(-q T D （2） D 2 D T τ) + b2exp(- (q 2 D T + D R )τ), wherein, b0, b1 and b2 are constant coefficients, q is the modulus of the scattering vector, D T is the translational diffusion coefficient, τ is the delay time, and D R is the rotational diffusion coefficient; Uncertainty analysis is performed on the solution of the nano-particles to be measured.

9. The dynamic light scattering method according to claim 8, wherein, Further comprising installing a fifth mirror, a beam combiner, a sixth mirror, a seventh mirror and an eighth mirror, and then collimating the light; The first mirror is rotated by a preset angle by the rotating mechanism so that the probe light enters from the first window at an incident angle of -160°-170° or 160°-170°.

10. The method according to claim 8, wherein the dynamic light scattering experiment is performed in a dynamic light scattering instrument. calculating the refractive index n of the solution of the nanoparticles under test fluid comprising: Adjusting the probe light to be perpendicular to the second window of the experimental body, the position on the profile analyzer is marked as point M, rotating the experimental body through an angle rotating mechanism, the position on the profile analyzer is marked as point N, L MN The offset distance of the probe light passing through the third window The refractive index n of the solution of the nano-particles to be measured is calculated according to a set of geometric-optical relation calculation formulas fluid wherein the set of geometric-optical relation calculation formulas is: ； In the formula, n fluid is the refractive index of the solution of the nanoparticles to be measured, k is the incident angle of the probe light at the inner wall surface of the third window, n glass is the refractive index of the material of the third window, a is the refraction angle of the probe light at the inner wall surface of the third window, b is the incident angle of the probe light at the outer wall surface of the third window, n air is the refractive index of air, g is the refraction angle of the probe light at the outer wall surface of the third window, L MN is the offset distance of the probe light from the third window, L2 is the distance between the outer wall surface of the third window and the profilometer, and L1 is the vertical distance of the probe light between the incident point on the inner wall surface of the third window and the outer wall surface.

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