A surface enhanced Raman scattering file card and its manufacturing method

Abstract

The present invention provides a surface enhanced Raman scattering file card and a method for making the same. The surface enhanced Raman scattering file card of the present invention comprises: a relative scattering cross section of "surface enhanced Raman scattering" of a selected molecule; and a relative scattering ability factor of "surface enhanced Raman scattering" of a selected molecule and a reference molecule. The surface enhanced Raman scattering file card constructed by the present invention for quantitative analysis has universal parameters between the same type of surface enhanced Raman scattering substrates with the same surface properties but different geometrical morphologies, and can eliminate the influence of factors such as uniformity of the surface enhanced Raman scattering substrate, batch differences, fluctuations in test conditions, and changes in geometrical morphology on quantitative analysis. It can be used to construct a quantitative analysis database in the field of SERS, and can enable SERS technology to conveniently carry out various quantitative analyses, just like X-ray diffraction technology has a standard powder diffraction card library.

Description

Technical Field

[0001] The invention relates to a surface enhanced Raman scattering file card and a manufacturing method thereof, and belongs to the field of chemical semi-quantitative and quantitative analysis. Background Art

[0002] Surface enhanced Raman scattering (SERS) is an inelastic scattering spectroscopy technique with ultra-high sensitivity and fingerprint recognition. At the same time, due to the fast acquisition speed of SERS spectroscopy, simple sample preparation, and continuous miniaturization of detection equipment, SERS spectroscopy has broad application prospects in the fields of environmental pollutant detection, food additive detection, pesticide residue detection, biochemical detection, pharmaceutical analysis and health screening. Since the discovery of the SERS phenomenon in 1974, SERS spectroscopy technology has developed for nearly half a century. For SERS spectroscopy technology, the SERS substrate is the key carrier for the target to produce a huge Raman scattering signal enhancement. With the continuous in-depth development of research, a variety of SERS substrates have been designed and applied to detection and analysis, including traditional precious metal SERS substrates, semiconductor SERS substrates, flexible SERS substrates, etc. Traditional precious metal SERS substrates are mainly nanostructures prepared from gold, silver, copper and their alloys. With the deepening of the understanding of the SERS mechanism, semiconductor SERS substrates are also developing continuously. At the same time, the development of flexible SERS substrates and the integration of other technologies such as atomic force microscopy and electrochemical technology with SERS spectroscopy are also continuously expanding the application scenarios and scope of SERS spectroscopy. This has made great progress in the detection of trace substances in SERS spectroscopy. Although great progress has been made in the design and preparation of SERS substrates and in detection and analysis, how to improve the stability, uniformity and repeatability of SERS substrates and how to reduce the differences between different batches of SERS substrates are still important research directions in this field. Because the stability, uniformity, repeatability and batch differences of SERS substrates are crucial to semi-quantitative and quantitative analysis based on SERS spectroscopy.

[0003] At present, in the field of quantitative analysis based on SERS spectroscopy, a variety of quantitative analysis methods have been developed and established. Linear, logarithmic, power-law and other functional relationships between the absolute intensity of SERS spectra and the concentration of the target are often used for quantitative analysis, but such methods have high requirements on the uniformity, repeatability and batch-to-batch variability of the substrate. The quantitative analysis method developed by combining the relative intensity information of SERS spectra with the above functional relationship aims to overcome the interference of SERS spectral intensity fluctuations on quantitative analysis. The quantitative analysis using the relative intensity information of SERS spectra includes constructing a core-shell SERS substrate containing an internal standard reference molecule modified only on the surface of the SERS substrate, constructing a core-shell SERS substrate containing an internal standard molecule in the shell layer, and correcting the intensity fluctuation of the target SERS spectrum using the Raman scattering characteristic peak of the internal standard reference molecule or the Raman scattering characteristic peak of the SERS substrate substrate, thereby effectively overcoming the influence of the absolute intensity fluctuation of the SERS spectrum on quantitative analysis. Since the physical nature behind the quantitative analysis method based on the relative intensity of SERS spectra is not discussed in depth, a universal semi-quantitative and quantitative analysis method has not yet been established in the field of SERS spectral quantitative analysis. In other analytical characterization techniques, relative factors are commonly used methods for semi-quantitative and quantitative analysis. For example, in X-ray diffraction and X-ray photoelectron spectroscopy, the relative sensitivity factors of different phases and elements can be used for quantitative analysis of phases and sample surface elements. Summary of the invention

[0004] Problem that the invention aims to solve

[0005] In response to the problems arising in the quantitative analysis process of SERS spectral detection, the inventors, starting from the basic physical concepts and drawing on the general quantitative analysis methods in technologies such as X-ray diffraction and X-ray photoelectron spectroscopy, provide a surface enhanced Raman scattering file card with wide versatility that can be used for semi-quantitative and quantitative analysis, and a method for making the same.

[0006] Solutions for solving problems

[0007] The present invention provides a surface enhanced Raman scattering file card, the file card comprising:

[0008] Relative scattering cross sections of “surface enhanced Raman scattering” of selected molecules;

[0009] Relative scattering power factor of the selected molecule compared to the reference molecule for Surface Enhanced Raman Scattering.

[0010] According to the surface enhanced Raman scattering file card of the present invention, the file card includes the material of the surface enhanced Raman scattering substrate and the test wavelength.

[0011] According to the surface enhanced Raman scattering file card of the present invention, the file card includes selected reference peaks of selected molecules and reference molecules.

[0012] According to the surface enhanced Raman scattering file card of the present invention, the file card comprises a normalized surface enhanced Raman scattering spectrum of a selected molecule.

[0013] The present invention also provides a method for making the surface enhanced Raman scattering file card according to the present invention, comprising the following steps:

[0014] Determine the "surface enhanced Raman scattering" spectrum of the selected molecule, select the characteristic peak with the strongest peak intensity in the spectrum as the reference peak, calculate the relative value of the peak intensity of other characteristic peaks and the peak intensity of the reference peak, and obtain the relative scattering cross section of the "surface enhanced Raman scattering";

[0015] The "surface enhanced Raman scattering" spectra of the selected molecule and the reference molecule are measured respectively, and the characteristic peaks with the strongest peak intensity in the spectra of the selected molecule and the reference molecule are selected as the reference peaks of the selected molecule and the reference molecule respectively. The "surface enhanced Raman scattering" spectrum of the mixture of the selected molecule and the reference molecule is measured, and the relative value of the peak intensity of the reference peak of the selected molecule and the reference molecule is calculated to obtain the relative scattering ability factor of the "surface enhanced Raman scattering".

[0016] According to the production method of the present invention, after selecting the characteristic peak with the strongest peak intensity in the spectrum as the reference peak, the intensity value of the reference peak is set to 100, and the peak intensities of other characteristic peaks are normalized. After normalization, the peak intensities of other characteristic peaks are the relative scattering cross sections of "surface enhanced Raman scattering".

[0017] According to the preparation method of the present invention, the selected molecule and the reference molecule are mixed in different molar ratios, and the "surface enhanced Raman scattering" spectra of different molar ratios are measured respectively, and the characteristic peaks with the strongest peak intensity in the spectra of the selected molecule and the reference molecule are respectively selected as the reference peaks of the selected molecule and the reference molecule, and the intensity ratio of the reference peaks of the selected molecule and the reference molecule is calculated. The linear regression coefficient between the intensity ratio and the molar ratio is calculated by the least squares regression method, which is the relative scattering ability factor of the "surface enhanced Raman scattering" between molecules.

[0018] According to the manufacturing method of the present invention, the intensity ratio is in the range of 0.1 to 10.

[0019] According to the production method described in the present invention, when measuring the "surface enhanced Raman scattering" spectrum, the molecule to be tested is dropped onto the surface of the substrate in the form of a solution. After the solvent is naturally dried, its spectrum is tested and the fluorescence background signal is subtracted to obtain the "surface enhanced Raman scattering" spectrum.

[0020] According to the preparation method of the present invention, the total concentration of the solution is 10 -8 ~10 -5 mol / L, the average intra-surface volume range of the drop amount is 0.1~5μL / mm 2 .

[0021] Effects of the Invention

[0022] The present invention constructs a surface enhanced Raman scattering file card that can be used for quantitative analysis by defining and measuring two physical quantities, the relative scattering cross section and the relative scattering capacity factor of "surface enhanced Raman scattering" within a molecule, wherein each parameter is universal between the same type of surface enhanced Raman scattering substrates with the same surface properties but different geometrical morphologies, and can eliminate the influence of factors such as the uniformity of the surface enhanced Raman scattering substrate, the difference between batches, the fluctuation of test conditions, the change of geometrical morphology and the like on the quantitative analysis, and can be used to construct a quantitative analysis database in the field of SERS, and can enable the SERS technology to conveniently carry out various quantitative analyses like the X-ray diffraction technology has a standard powder diffraction card library, and has broad application prospects and an important basic supporting role in the field of quantitative analysis of trace molecules. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Reflectivity spectra and SEM images of 90nm silver nanorod structure substrate, 700nm silver nanorod structure substrate, and V-shaped silver nanorod structure substrate with a single arm length of 350nm;

[0024] Figure 2 SERS spectra of 4-MBA molecules on the surface of silver nanorod structure substrate at 490nm under different laser powers and normalized SERS spectra after deducting the fluorescence background signal;

[0025] Figure 3 The SERS spectra of 4-MBA and 2-MPY molecules tested on silver SERS substrates with different structures and the normalized SERS spectra after deducting the fluorescence background signal;

[0026] Figure 4 SERS spectra of mixed solutions of 4-MBA and 2-MPY with a molecular ratio of 9:1 and 1:9 on silver SERS substrates with different structures and normalized SERS spectra after background subtraction;

[0027] Figure 5 The relative scattering power factor of SERS between 4-MBA and 2-MPY molecules measured by the mixed dropping method;

[0028] Figure 6The SERS file card of 2-MPY molecule is constructed based on the measured relative scattering cross section within 2-MPY molecule and the relative scattering ability factor of SERS between 2-MPY and 4-MBA molecules; DETAILED DESCRIPTION

[0029] Definition and derivation of physical quantities

[0030] The SERS process includes the adsorption process of molecules on the surface of the SERS substrate, the Raman scattering process of molecules, and the enhancement process of the SERS substrate on the Raman scattering of molecules. peak,i ) and laser power (L λ ), the number of molecules (N m ), the SERS characteristic peak scattering cross section of the molecule on the substrate surface (σ SERS,peak,i ), as shown in the following formula (1):

[0031] I peak,i ∝L λ N m σ SERS,peak,i (1-1)

[0032] The same molecule generally has multiple Raman scattering characteristic peaks. In the SERS spectrum, the same molecule also has multiple SERS characteristic peaks. For different SERS characteristic peaks of the same molecule, select one of the SERS characteristic peaks (σ SERS,peak,r ) as a reference, (1) can be equivalently transformed into the following formula (1-2):

[0033]

[0034] Then it is transformed into the following formula (1-3):

[0035]

[0036] The inventors found that, now define (1-3) in the formula is the relative SERS cross section (RCS) between different SERS peaks of the same molecule, that is, the following formula (1-4) holds true:

[0037]

[0038] The SERS relative scattering cross section is mathematically equivalent to normalizing the SERS spectrum of a molecule with a selected SERS characteristic peak. This normalization preserves the intensity relationship between different SERS characteristic peaks of the molecule while eliminating the fluctuation of the absolute intensity.

[0039] According to the above definition, for two different molecules M1 and M2, the following equations (1-5) and (1-6) are respectively established:

[0040]

[0041]

[0042] where σ SERS,peak,r,M1 and σ SERS,peak,r,M2 are the SERS characteristic peak scattering cross sections selected from the two molecules M1 and M2. Now define the ratio of the two is the relative SERS scattering ability factor (RSA) between molecules, which is shown in the following formula (1-7):

[0043]

[0044] Dividing formula (1-6) by formula (1-5), we can get the following formula (1-8):

[0045]

[0046] Substituting equations (1-4) and (1-7) into equation (1-8), we can obtain equation (1-9):

[0047]

[0048] RSF M2 / M1 is the relative SERS scattering ability factor (RSA) of molecule M2 relative to molecule M1, RCS M1 、RCS M2 are the SERS relative scattering cross sections (RCS) of molecules M1 and M2 respectively. For equation (1-9), it can be transformed into the following equation (1-10):

[0049]

[0050] According to formula (1-10), quantitative analysis can be carried out to directly calculate the relative content information between molecules. Similarly, formula (1-10) can be transformed into formula (1-11):

[0051]

[0052] According to formula (1-11), the number of molecules of molecule M2 can be directly calculated.

[0053] It can be seen from formula (1-10) that the relative content of molecules can be calculated through the two defined physical quantities, intramolecular SERS relative scattering cross section (RCS) and intermolecular SERS relative scattering ability factor (RSA) and SERS spectrum; it can be seen from formula (1-11) that the number of molecules M2 can be solved through the two defined physical quantities RCS and RSA, combined with the SERS spectrum and the number of molecules M1.

[0054] According to the above definition and discussion of the inventors, if the two parameters of RCS and RSA of a molecule are obtained, they can be used for quantitative analysis of the molecular content and the number of molecules. The measurement methods of these two physical quantities will be described below.

[0055] Verification of the relative scattering cross section of "surface enhanced Raman scattering"

[0056] First, to verify the validity of the relative scattering cross section of "surface enhanced Raman scattering", a variety of silver SERS substrates with different structures are provided, and their SEM photos are as follows: Figure 1 (bd) are 490nm silver nanorod structure substrate, 700nm silver nanorod structure substrate, and V-shaped silver nanorod structure substrate with a single arm length of 350nm. The reflectivity spectra of three different nanostructured SERS substrates are shown in Figure 1 As shown in (a), Figure 1 (a) It can be seen that the three different structures have different optical properties. There are significant differences in reflectivity at different wavelengths. The valley values ​​of the reflectivity curves and the shapes of the reflection valleys are different.

[0057] use Figure 1 (b) The 490nm silver nanorod structure substrate is tested at different laser powers to obtain the SERS spectra of 4-mercaptobenzoic acid (4-MBA) molecules. The SERS spectra of 4-MBA molecules tested at different laser powers are shown in Figure 2. Figure 2 As shown in (a), the spectral intensity varies with different laser powers. The SERS spectra obtained by different laser power tests are normalized after deducting the background. -1 The SERS characteristic peak is selected as the reference peak, and its intensity is taken as 100, and the normalized SERS spectrum can be obtained as follows: Figure 2 As shown in (b), it can be seen from the figure that the normalized SERS spectra of 4-MBA molecules at different powers are almost completely overlapped.

[0058] Similarly, for the silver SERS substrates with different structures, the SERS spectra of 4-MBA molecules obtained under the same test conditions are as follows: Figure 3 As shown in (a), it can be seen from the figure that the enhancement effects of SERS substrates with different structures are different, and the intensity difference between them is huge. Figure 3The spectrum in (a) is background-subtracted at 1074 cm -1 The SERS characteristic peak is normalized as the reference peak, and the following can be obtained: Figure 3 (b) shows the results. It can be seen from the figure that the normalized SERS spectra of 4-MBA molecules tested by different nanostructured SERS substrates are almost completely overlapped. Similarly, for 2-thiopyridine (2-MPY) molecules, Figure 3 (c) The SERS spectra of 2-MPY molecules obtained by testing the silver SERS substrates with different structures mentioned above, with the background subtracted and the wavelength at 1002 cm -1 The SERS characteristic peak is normalized as the reference peak, and the following can be obtained: Figure 3 (d) shows the result that the spectra almost completely overlap after normalization.

[0059] From the above analysis, it can be seen that the relative scattering cross section of SERS within a molecule is a general parameter of the system composed of molecules and SERS substrate materials. For SERS substrates of the same material, the changes in test laser power and nanostructure geometric morphology can be ignored.

[0060] Verification of the relative scattering power factor of "surface enhanced Raman scattering"

[0061] The relative SERS scattering factor between molecules requires measuring the SERS spectra of solutions of two molecules mixed in different proportions. First, 4-MBA and 2-MPY molecules are mixed in different proportions, dripped onto the surface of the silver SERS substrates with different structures, and then naturally dried to obtain the SERS spectra of the two molecules mixed in different proportions. Figure 4 The mixed SERS spectra of two molecules 4-MBA and 2-MPY with a mixing ratio of 1:9 and 9:1 are given. Figure 4 As shown in (a), the mixing ratio of 4-MBA and 2-MPY molecules is 1:9. The SERS spectra obtained on the silver SERS substrates with different structures have great differences in intensity. The SERS spectra after background subtraction are taken at 1002 cm -1 After normalizing the SERS characteristic peaks, we can get Figure 4 As shown in (b), the SERS spectra of the three silver SERS substrates with different structures are almost completely overlapped. Figure 4 As shown in (c), the mixing ratio of 4-MBA and 2-MPY molecules is 9:1. The SERS spectra obtained on the silver SERS substrates with different structures have great differences in intensity. The SERS spectra after background subtraction are taken at 1074 cm -1 After normalizing the SERS characteristic peaks, we can get Figure 4(d) shows that the SERS spectra obtained by the three different structures of silver SERS substrates are almost completely overlapped. This shows that when the SERS substrate material is the same, the geometric morphology of the SERS substrate nanostructure has little effect on the measurement results of the mixed SERS spectrum. The relative scattering power factor of the SERS between molecules measured based on this is a general parameter of the system composed of molecules and SERS substrates.

[0062] Since the relative SERS scattering cross section within a molecule and the relative SERS scattering ability factor between molecules are general parameters between molecules and SERS substrates, they can be used to construct data files and conduct quantitative analysis. Figure 4 (cd) It can be seen that when the molecular ratio of 4-MBA to 2-MPY is 9:1, the spectrum is mainly composed of the signal of 4-MBA. In this case, the slight signal and noise fluctuations will have a great impact on the measurement of the relative SERS scattering ability factor between the two molecules, that is, it is necessary to calculate the relative SERS scattering cross section between the two molecules when the difference in the signal intensity of the two molecules is not large. First, five mixed solutions with different ratios of 4-MBA and 2-MPY molecules of 1:9, 2:8, 3:7, 4:6, and 5:5 were prepared, and the five mixed solutions were dripped onto the surfaces of different nanostructured SERS substrates, and their SERS spectra were tested after natural drying. The relative intensities of the reference peaks selected by the two molecules in the mixed SERS spectra of the two molecules in each ratio were calculated, and the relative intensities of the two were plotted against the molecular number ratio. The results are shown in FIG. Figure 5 As shown in the figure, the results obtained from the three different structures of silver SERS substrates are all Figure 5 As shown in the figure, the three test results are not much different. The measured results are linearly fitted, and the slope is the relative SERS scattering ability factor between the two molecules. From the fitting results, it can be seen that the relative SERS scattering ability factors between 4-MBA molecules and 2-MPY molecules obtained from the three different structure SERS substrate tests are not much different.

[0063] In summary, the relative SERS scattering cross section within a molecule and the relative SERS scattering ability factor between molecules are general parameters of the system composed of molecules and SERS substrate materials. They are insensitive to the geometric morphology of the SERS substrate and can be used as general parameters to construct SERS file cards and conduct quantitative analysis.

[0064] Surface Enhanced Raman Scattering File Card

[0065] Based on the above analysis, the present invention provides a surface enhanced Raman scattering file card, the file card comprising:

[0066] Relative scattering cross sections of “surface enhanced Raman scattering” of selected molecules;

[0067] Relative scattering power factor of the selected molecule compared to the reference molecule for Surface Enhanced Raman Scattering.

[0068] According to the surface enhanced Raman scattering file card of the present invention, the file card includes the material and test wavelength of the surface enhanced Raman scattering substrate. Since the values ​​of the two physical quantities are related to the test wavelength of the laser and the material of the SERS substrate, the above information should be noted in the SERS file.

[0069] According to the surface enhanced Raman scattering file card of the present invention, the file card includes selected reference peaks of selected molecules and reference molecules.

[0070] According to the surface enhanced Raman scattering file card of the present invention, the file card includes the normalized surface enhanced Raman scattering spectrum of the selected molecule. The relative scattering cross section of the intramolecular SERS has different values ​​at different Raman shifts, so it is necessary to give the normalized SERS spectrum of the molecule, and the normalized SERS spectrum here refers to the relative SERS spectrum when the selected SERS reference peak intensity is taken as 100. In order to carry out qualitative and quantitative analysis more simply and directly, the main characteristic peaks and relative intensities of the SERS spectrum and their corresponding Raman vibration modes should be listed in the SERS file card.

[0071] The present invention also provides a database comprising surface enhanced Raman scattering file cards of more than one molecule.

[0072] Quantitative analysis can be conveniently carried out based on the established SERS file card, and the information in the SERS file card can be used for quantitative analysis in different situations. When the SERS characteristic peaks between different molecules are easy to distinguish in the SERS spectrum, the relative intensity ratio between the characteristic peaks of different molecules can be calculated first, and then the relative scattering cross section of SERS and the relative scattering power factor of SERS in the SERS file card can be used to realize the quantitative analysis of the relative content between molecules; when the SERS characteristic peaks between different molecules are not easy to distinguish in the SERS spectrum, the normalized SERS spectrum in the SERS file card can be multiplied by the relative scattering power factor of SERS to obtain the relative SERS spectra of different molecules, and then the ratio of the relative SERS spectra of each molecule contained in the SERS spectrum to be analyzed can be solved by using a suitable algorithm, and this ratio is the content ratio of each molecule; for the concentration analysis of the target molecule, the appropriate reference molecule can be first selected according to the SERS file card, and then the reference molecule of known concentration is added to the system to be analyzed, and by measuring the SERS spectrum, the relative content ratio of the reference molecule and the target molecule is first calculated according to the two parameters in the SERS file card, and then the concentration of the target molecule is solved according to the concentration of the added reference molecule and the calculated relative content ratio.

[0073] Method for making surface enhanced Raman scattering file card

[0074] The present invention provides a method for manufacturing a surface enhanced Raman scattering file card according to the present invention, characterized in that it comprises the following steps:

[0075] Determine the "surface enhanced Raman scattering" spectrum of the selected molecule, select the characteristic peak with the strongest peak intensity in the spectrum as the reference peak, calculate the relative value of the peak intensity of other characteristic peaks and the peak intensity of the reference peak, and obtain the relative scattering cross section of the "surface enhanced Raman scattering";

[0076] The "surface enhanced Raman scattering" spectra of the selected molecule and the reference molecule are measured respectively, and the characteristic peaks with the strongest peak intensity in the spectra of the selected molecule and the reference molecule are selected as the reference peaks of the selected molecule and the reference molecule respectively. The "surface enhanced Raman scattering" spectrum of the mixture of the selected molecule and the reference molecule is measured, and the relative value of the peak intensity of the reference peak of the selected molecule and the reference molecule is calculated to obtain the relative scattering ability factor of the "surface enhanced Raman scattering".

[0077] Determination of relative scattering cross section of surface enhanced Raman scattering

[0078] According to the production method of the present invention, after selecting the characteristic peak with the strongest peak intensity in the spectrum as the reference peak, the intensity value of the reference peak is set to 100, and the peak intensities of other characteristic peaks are normalized. After normalization, the peak intensities of other characteristic peaks are the relative scattering cross sections of "surface enhanced Raman scattering".

[0079] Preferably, for the relative scattering cross section (RCS) of the SERS spectrum of the selected molecule, according to formula (1-4), a certain SERS characteristic peak can be selected as a reference peak, and the relative scattering cross sections of the SERS of other peaks can be calculated. Specific operation: measure the spectrum of the selected molecule on the SERS substrate, deduct the background signal such as fluorescence from the SERS spectrum obtained by the test, select the characteristic peak with the strongest peak intensity of the SERS spectrum as the reference peak, perform normalization processing, and calculate the relative intensity of any other characteristic peak, which is the relative scattering cross section of the SERS.

[0080] Determination of the relative scattering power factor of "surface enhanced Raman scattering"

[0081] According to the preparation method of the present invention, the selected molecule and the reference molecule are mixed in different molar ratios, and the "surface enhanced Raman scattering" spectra of different molar ratios are measured respectively, and the characteristic peaks with the strongest peak intensity in the spectra of the selected molecule and the reference molecule are respectively selected as the reference peaks of the selected molecule and the reference molecule, and the intensity ratio of the reference peaks of the selected molecule and the reference molecule is calculated. The linear regression coefficient between the intensity ratio and the molar ratio is calculated by the least squares regression method, which is the relative scattering ability factor of the "surface enhanced Raman scattering" between molecules.

[0082] According to the manufacturing method of the present invention, the intensity ratio is in the range of 0.1 to 10.

[0083] According to the production method described in the present invention, when measuring the "surface enhanced Raman scattering" spectrum, the molecule to be tested is dropped onto the surface of the substrate in the form of a solution. After the solvent is naturally dried, its spectrum is tested and the fluorescence background signal is subtracted to obtain the "surface enhanced Raman scattering" spectrum.

[0084] According to the preparation method of the present invention, the total concentration of the solution is 10 -8 ~10 -5 mol / L, the average intra-surface volume range of the drop amount is 0.1~5μL / mm 2 .

[0085] Example

[0086] Example 1

[0087] Step 1. Prepare a 490nm silver nanorod structure substrate with a purity of 99.99% by using an electron beam tilted deposition method;

[0088] Step 2. Separately add 10 μL of -5 The 4-mercaptobenzoic acid (4-MBA) molecular solution and the 2-mercaptopyridine (2-MPY) molecular solution were dripped onto the surface of a 10 mm × 10 mm silver nanorod structure substrate with a diameter of 490 nm. After being dried naturally, the SERS spectrum was tested using a 785 nm laser and the fluorescence background signal of the SERS spectrum was subtracted.

[0089] Step 3. For the SERS spectrum after deducting the fluorescence background signal in step 2, select the 1074 cm -1 The characteristic peaks and 1002 cm of the SERS spectrum of 2-MPY molecules -1 The characteristic peak is taken as the reference peak, and its intensity is taken as 100. The SERS spectra of the two molecules are normalized to obtain the relative scattering cross section of SERS at different Raman shifts.

[0090] Step 4. Mix 4-MBA molecules and 2-MPY molecules respectively. The molecular ratios of the mixed solutions are 1:9, 2:8, 3:7, 4:6, 5:5, and the total concentration of the mixed solution is 10 -5 M, 10 μL of each mixed solution was dropped onto the surface of a 5 mm × 5 mm silver nanorod structure substrate with a diameter of 490 nm, and the SERS spectrum was tested after natural drying, and the fluorescence background signal was subtracted;

[0091] Step 5. Calculate the 1074 cm-1 of the 4-MBA molecule in the SERS spectrum after deducting the fluorescence background signal in step 4. -1 Characteristic peak and -MPY molecule 1002cm -1 The intensity ratio of the characteristic peaks is calculated by the least squares regression method. The linear regression coefficient of the intensity ratio of the two and the corresponding molar ratio in the mixed solution is the relative SERS scattering ability factor between the two: corresponding to the molecular number ratio in step 4, 4-MBA molecule 1074cm -1 Characteristic peak and 2-MPY molecule 1002cm -1 The intensity ratios of the characteristic peaks were 0.35 ± 0.03, 1.14 ± 0.09, 3.86 ± 0.34, 4.76 ± 0.23, and 6.25 ± 0.63;

[0092] Step 6. The substrate material in step 1, the test wavelength of the laser in step 2, the reference peak information in step 3, the normalized SERS spectrum in step 3, the relative scattering cross section of SERS in step 3, the relative scattering power factor of SERS in step 5, and the Raman vibration mode of each SERS characteristic peak are calculated. Figure 6 The forms shown are combined to establish the SERS file card between 2-MPY molecules and 4-MBA molecules.

[0093] The SEM image of the 490nm nanorod SERS substrate used is shown in Figure 1 (b) shows the reflectivity spectrum. Figure 1 As shown in (a), the normalized SERS spectra of the 4-MBA and 2-MPY molecules obtained by testing are as follows: Figure 3 As shown in (b) and (d), the calculated relative scattering power factor of the SERS of 4-MBA relative to 2-MPY molecules is 6.7 ± 1.1, as shown in Figure 5 as shown in .

[0094] Based on the above discussion and test results, the relative scattering cross section of SERS and the relative scattering power factor of SERS can be constructed as follows: Figure 6The SERS file card shown is just an example. From top to bottom, the SERS file card number, the material and test wavelength of the SERS substrate used, as well as the name of the molecule and the SERS reference peak of the selected molecule are shown. The lower part of the SERS file card continues to give two parameters that can be used for quantitative analysis: the relative scattering ability factor of SERS and the relative scattering cross section of SERS. The normalized SERS spectrum of the molecule and the structural formula of the molecule are listed in the middle. In order to conduct qualitative and quantitative analysis more easily and directly, the table at the bottom of the SERS file card lists the main SERS characteristic peaks of the 2-MPY molecule and their relative intensities, as well as their corresponding Raman vibration modes.

[0095] Example 2

[0096] Step 1. Prepare a 700nm silver nanorod structure substrate with a purity of 99.99% by using an electron beam tilted deposition method;

[0097] Step 2. Separately add 10 μL of -6 The 4-mercaptobenzoic acid (4-MBA) molecular solution and the 2-mercaptopyridine (2-MPY) molecular solution were dripped onto the surface of a 700nm silver nanorod structure substrate with an area of ​​5mm×5mm. After being dried naturally, the SERS spectrum was tested using a 785nm laser and the fluorescence background signal of the SERS spectrum was subtracted.

[0098] Step 3. For the SERS spectrum after deducting the fluorescence background signal in step 2, select the 1074 cm -1 The characteristic peaks and 1002 cm of the SERS spectrum of 2-MPY molecules -1 The characteristic peak is taken as the reference peak, and its intensity is taken as 100. The SERS spectra of the two molecules are normalized to obtain the relative scattering cross section of SERS at different Raman shifts.

[0099] Step 4. Mix 4-MBA molecules and 2-MPY molecules respectively. The molecular ratios of the mixed solutions are 1:9, 2:8, 3:7, 4:6, 5:5, and the total concentration of the mixed solution is 10 -6 M, 15 μL of each mixed solution was dropped onto the surface of a 700 nm silver nanorod structure substrate with an area of ​​5 mm×5 mm, and its SERS spectrum was tested after natural drying, and the fluorescence background signal was subtracted;

[0100] Step 5. Calculate the 1074 cm-1 of the 4-MBA molecule in the SERS spectrum after deducting the fluorescence background signal in step 4. -1 Characteristic peak and -MPY molecule 1002cm -1The intensity ratio of the characteristic peaks is calculated by the least squares regression method. The linear regression coefficient of the intensity ratio of the two and the corresponding molar ratio in the mixed solution is the relative SERS scattering ability factor between the two: corresponding to the molecular number ratio in step 4, 4-MBA molecule 1074cm -1 Characteristic peak and 2-MPY molecule 1002cm -1 The intensity ratios of the characteristic peaks were 0.38 ± 0.02, 0.92 ± 0.12, 3.21 ± 0.32, 3.56 ± 0.24, and 6.08 ± 0.67;

[0101] Step 6. The substrate material in step 1, the test wavelength of the laser in step 2, the reference peak information in step 3, the normalized SERS spectrum in step 3, the relative scattering cross section of SERS in step 3, the relative scattering power factor of SERS in step 5, and the Raman vibration mode of each SERS characteristic peak are calculated. Figure 6 The forms shown are combined to establish the SERS file card between 2-MPY molecules and 4-MBA molecules.

[0102] The SEM image of the 700nm nanorod SERS substrate used is shown in Figure 1 (c) shows that its reflectance spectrum is Figure 1 As shown in (a), the calculated relative scattering power factor of the SERS of 4-MBA relative to 2-MPY molecules is 6.3 ± 0.8, as shown in Figure 5 as shown in .

[0103] Example 3

[0104] Step 1. Prepare a V-shaped silver nanorod structure substrate with a purity of 99.99% and an arm length of 350 nm by using an electron beam tilted deposition method;

[0105] Step 2. Separately add 15 μL of -6 The 4-mercaptobenzoic acid (4-MBA) molecular solution and the 2-mercaptopyridine (2-MPY) molecular solution were dripped onto the surface of a 700nm silver nanorod structure substrate with an area of ​​5mm×5mm. After being dried naturally, the SERS spectrum was tested using a 785nm laser and the fluorescence background signal of the SERS spectrum was subtracted.

[0106] Step 3. For the SERS spectrum after deducting the fluorescence background signal in step 2, select the 1074 cm -1 The characteristic peaks and 1002 cm of the SERS spectrum of 2-MPY molecules -1The characteristic peak is taken as the reference peak, and its intensity is taken as 100. The SERS spectra of the two molecules are normalized to obtain the relative scattering cross section of SERS at different Raman shifts.

[0107] Step 4. Mix 4-MBA molecules and 2-MPY molecules respectively. The molecular ratios of the mixed solutions are 1:9, 2:8, 3:7, 4:6, 5:5, and the total concentration of the mixed solution is 10 -6 M, 15 μL of each mixed solution was dropped onto the surface of a 5 mm × 5 mm V-shaped silver nanorod structure substrate with an arm length of 350 nm, and its SERS spectrum was tested after natural drying, and the fluorescence background signal was subtracted;

[0108] Step 5. Calculate the 1074 cm-1 of the 4-MBA molecule in the SERS spectrum after deducting the fluorescence background signal in step 4. -1 Characteristic peak and -MPY molecule 1002cm -1 The intensity ratio of the characteristic peaks is calculated by the least squares regression method. The linear regression coefficient of the intensity ratio of the two and the corresponding molar ratio in the mixed solution is the relative SERS scattering ability factor between the two: corresponding to the molecular number ratio in step 4, 4-MBA molecule 1074cm -1 Characteristic peak and 2-MPY molecule 1002cm -1 The intensity ratios of the characteristic peaks were 0.36±0.02, 0.96±0.18, 2.83±0.07, 4.89±0.25, and 5.98±0.51;

[0109] Step 6. The substrate material in step 1, the test wavelength of the laser in step 2, the reference peak information in step 3, the normalized SERS spectrum in step 3, the relative scattering cross section of SERS in step 3, the relative scattering power factor of SERS in step 5, and the Raman vibration mode of each SERS characteristic peak are calculated. Figure 6 The forms shown are combined to establish the SERS file card between 2-MPY molecules and 4-MBA molecules.

[0110] The SEM image of the 350nm nano-arm length V-shaped nanorod SERS substrate used is shown in Figure 1 (d) shows the reflectivity spectrum. Figure 1 As shown in (a), the calculated relative scattering power factor of the SERS of 4-MBA relative to 2-MPY molecules is 6.7 ± 0.9, as shown in Figure 5 as shown in .

[0111] According to the results measured in Examples 1-3, the average value of 6.7±1.1, 6.3±0.8, and 6.7±0.9 was calculated to be 6.56±0.54, that is, the relative scattering ability factor of the SERS of 4-MBA relative to that of 2-MPY molecules was 6.56±0.54.

[0112] Based on the above discussion, we can Figure 6 The relative scattering cross section and relative scattering capacity factor in the established SERS file card were used to carry out quantitative analysis of the relative content of 4-MBA and 2-MPY molecules in the solution and the concentration of 2-MPY molecules.

[0113] In order to achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents.

Claims

1. A surface enhanced Raman scattering file card, the file card comprising: Relative scattering cross section of "surface enhanced Raman scattering" of selected molecules; The relative scattering power factor of "surface enhanced Raman scattering" of the selected molecule and the reference molecule; Among them, the characteristic peak intensity of surface enhanced Raman scattering obtained by surface enhanced Raman scattering test is I peak,i With laser power L λ 、Number of molecules m , the characteristic peak scattering cross section σ of the surface enhanced Raman scattering of molecules on the substrate surface SERS,peak,i is proportional to, as shown in the following formula (1-1): I peak,i ∝L λ N m σ SERS,peak,i (1-1); In the surface enhanced Raman scattering spectrum, the same molecule also has multiple surface enhanced Raman scattering characteristic peaks. For different surface enhanced Raman scattering characteristic peaks of the same molecule, one of the characteristic peaks σ is selected SERS,peak,r As a reference, (1-1) is equivalently transformed into the following formula (1-2): Then it is transformed into the following formula (1-3): Define (1-3) is the relative scattering cross section RCS of the surface enhanced Raman scattering between different surface enhanced Raman scattering peaks of the same molecule, that is, the following formula (1-4) holds: According to the above definition, for two different molecules, namely the reference molecule M1 and the selected molecule M2, the following equations (1-5) and (1-6) are respectively established: where σ SERS,peak,r,M1 and σ SERS,peak,r,M2 The reference molecule M1 and the selected molecule M2 are the characteristic peak scattering cross sections of the surface enhanced Raman scattering selected from the two molecules, and the ratio of the two is defined as the relative scattering ability factor of the surface enhanced Raman scattering between molecules, which is shown in the following formula (1-7): Dividing formula (1-6) by formula (1-5), we can get the following formula (1-8): Substituting equations (1-4) and (1-7) into equation (1-8), we can obtain equation (1-9): RSF M2 / M1 RCS is the relative scattering power factor of the surface enhanced Raman scattering of the selected molecule M2 relative to the reference molecule M1. M1 、RCS M2 are the relative scattering cross sections (RCS) of surface enhanced Raman scattering of the reference molecule M1 and the selected molecule M2, respectively.

2. The surface enhanced Raman scattering file card according to claim 1, characterized in that: The file card includes the material and test wavelength of the surface enhanced Raman scattering substrate.

3. The surface enhanced Raman scattering file card according to claim 1 or 2, characterized in that: The file card includes the selected molecule and the selected reference peak of the reference molecule.

4. The surface enhanced Raman scattering file card according to claim 1 or 2, characterized in that: The file card includes a normalized surface enhanced Raman scattering spectrum of a selected molecule.

5. A method for making a surface enhanced Raman scattering file card according to any one of claims 1 to 4, characterized in that: The steps include: Determine the "surface enhanced Raman scattering" spectrum of the selected molecule, select the characteristic peak with the strongest peak intensity in the spectrum as the reference peak, calculate the relative values ​​of the peak intensity of other characteristic peaks and the peak intensity of the reference peak, and obtain the relative scattering cross section of the "surface enhanced Raman scattering"; The "surface enhanced Raman scattering" spectra of the selected molecule and the reference molecule are measured respectively, and the characteristic peaks with the strongest peak intensities in the spectra of the selected molecule and the reference molecule are selected as the reference peaks of the selected molecule and the reference molecule respectively. The "surface enhanced Raman scattering" spectrum of the mixture of the selected molecule and the reference molecule is measured, and the relative value of the peak intensity of the reference peak of the selected molecule and the reference molecule is calculated to obtain the relative scattering ability factor of the "surface enhanced Raman scattering".

6. The method according to claim 5, characterized in that: After selecting the characteristic peak with the strongest peak intensity in the spectrum as the reference peak, the intensity value of the reference peak is set to 100, and the peak intensities of other characteristic peaks are normalized. After normalization, the peak intensities of other characteristic peaks are the relative scattering cross sections of "surface enhanced Raman scattering".

7. The manufacturing method according to claim 5, characterized in that: The selected molecule and the reference molecule are mixed at different molar ratios, and the "surface enhanced Raman scattering" spectra of different molar ratios are measured respectively. The characteristic peaks with the strongest peak intensity in the spectra of the selected molecule and the reference molecule are respectively selected as the reference peaks of the selected molecule and the reference molecule, and the intensity ratio of the reference peaks of the selected molecule and the reference molecule is calculated. The linear regression coefficient between the intensity ratio and the molar ratio is calculated by the least squares regression method, which is the relative scattering ability factor of the "surface enhanced Raman scattering" between the molecules.

8. The method according to claim 7, characterized in that: The intensity ratio is in the range of 0.1 to 10.

9. The production method according to any one of claims 5 to 8, characterized in that: When measuring the "surface enhanced Raman scattering" spectrum, the molecule to be tested is added dropwise to the substrate surface in the form of a solution. After the solvent is naturally dried, its spectrum is tested and the fluorescence background signal is subtracted to obtain the "surface enhanced Raman scattering" spectrum.

10. The manufacturing method according to claim 9, characterized in that: The total concentration of the solution is 10 -8 ~10 -5 mol / L, the average intra-surface volume range of the drop amount is 0.1~5μL / mm 2 .

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