Apparatus and method for measuring absolute quantum yield

Abstract

The application relates to a method for measuring absolute quantum yield, which comprises the following steps: S1, scanning a sample to be measured in a first predetermined wavelength range to obtain an emission spectrum curve S of the sample to be measured; S2, scanning a blank background in the first predetermined wavelength range to obtain a blank background curve B; S3, attenuating the signal of the blank background so that the signal intensity of the blank background falls within the linear response interval of an instrument detector, scanning the blank background in the first predetermined wavelength range to obtain an attenuated blank background curve BND; S4, scanning the sample to be measured in the first predetermined wavelength range to obtain an attenuated sample to be measured curve SND; and S5, deducting the influence caused by the attenuation to obtain the absolute quantum yield of the sample to be measured. The application also relates to a device for measuring absolute quantum yield. The measuring method can be used for accurately measuring the absolute quantum yield of weakly luminescent samples to be measured and moderately luminescent samples to be measured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of analytical detection and fluorescent material technology, and particularly relates to a measuring device and a measuring method for absolute quantum yield.

[0002] Blank background technology

[0003] The quantum yield of light refers to the ratio of the number of photons emitted by a fluorescent substance after absorbing light to the number of photons of the excitation light absorbed, and is a measure of the amount of fluorescence of the fluorescent substance. There are two common methods for measuring the quantum yield of a sample: relative quantum yield and absolute quantum yield. The relative quantum yield method requires a standard sample with a known quantum yield as a reference, and the quantum yield of the sample to be measured is obtained by measuring the absorbance and fluorescence intensity of the standard sample and the sample to be measured. This method is only suitable for liquid samples, and has a large subjective error. The absolute quantum yield method using an integrating sphere accessory combined with a spectrometer can overcome these problems, and has been widely used in recent years for measuring liquid and solid samples. SUMMARY

[0004] Although the absolute quantum yield method can be used to measure the absolute quantum yield of most liquid and solid fluorescent substances, the inventors have found in practice that the existing absolute quantum yield measuring device cannot accurately measure the absolute quantum yield of weakly luminescent fluorescent substances.

[0005] Specifically, when measuring the quantum yield of a strongly luminescent sample, only two spectral curves need to be measured, and the quantum yield of the sample can be obtained by mathematical operation and area integration of the two curves. The above is the commonly used absolute quantum yield measurement method, which is referred to as the two-line method (QYT) in the present application. However, it is very difficult to measure the quantum yield of a weakly luminescent sample using this method. This is because the detector of a fluorescence spectrometer has a linear response range, and the intensity of the excitation light source cannot be too high. When measuring the quantum yield of a weakly luminescent sample, the intensity of the light source is usually low, and the emission peak of the sample to be measured is usually small, making it difficult to detect and resulting in a large error. The intensity-dependent quantum yield measurement requires the excitation light source to have a high intensity and be adjustable. Therefore, the existing method has a large error when measuring the absolute quantum yield of a weakly luminescent sample, and cannot meet the requirements of intensity-dependent quantum yield measurement of a weakly luminescent sample.

[0006] The present application aims to provide a measurement method for accurately determining the absolute quantum yield of weakly luminescent fluorescent substances. Specifically, the measurement method described herein comprises first scanning the sample to be measured and a blank background without attenuating the signal to obtain a sample curve and a blank background curve. Then, the signal is attenuated so that the signal of the blank background falls within the linear response interval of the detector, and the blank background and the sample to be measured are scanned again to obtain an attenuated blank background curve and an attenuated sample curve. Through mathematical calculation between the obtained curves, the influence of attenuation can be eliminated, and the absolute quantum yield of the sample to be measured can be accurately calculated.

[0007] The present application also aims to provide a measurement device for accurately determining the absolute quantum yield of weakly luminescent fluorescent substances.

[0008] To solve the above technical problems, the present application provides the following technical solutions.

[0009] In a first aspect, the present application provides a measurement method for absolute quantum yield, comprising the following steps:

[0010] S1: Scanning the sample to be measured in a first predetermined wavelength range under the condition that the emitted partial signal of the sample to be measured can be directly detected by a detector to obtain a sample emission spectrum curve S;

[0011] S2: Replacing the sample to be measured with a blank background under the same detection conditions as in step S1, scanning the blank background in the first predetermined wavelength range to obtain a blank background curve B;

[0012] S3: Attenuating the signal of the blank background so that the signal of the emitted part of the blank background falls within the linear response interval of the detector, scanning the blank background in the first predetermined wavelength range to obtain an attenuated blank background curve BND;

[0013] S4: Replacing the blank background with the sample to be measured under the same detection conditions as in step S3, scanning the sample to be measured in the first predetermined wavelength range to obtain an attenuated sample curve SND; and,

[0014] S5: Subtracting the influence of attenuation to obtain the absolute quantum yield of the sample to be measured.

[0015] In an embodiment of the first aspect, in step S5, subtracting the influence of attenuation comprises calculating the absolute quantum yield of the sample to be measured according to the following formula (1):

[0016] QY F = [A S-B / A BND-SND ] / DB formula (1),

[0017] wherein QY F represents the absolute quantum yield of the sample to be measured, A S-B represents the spectral integral area of the emission signal of the sample to be measured, A BND-SND represents the spectral integral area of the absorption signal of the sample to be measured, and DB represents the attenuation factor;

[0018] wherein the emission signal of the sample to be measured is a spectrum obtained by subtracting the spectrum of the blank background curve B from the spectrum curve S of the sample to be measured;

[0019] wherein the absorption signal of the sample to be measured is a spectrum obtained by subtracting the spectrum of the attenuated blank background curve BND from the spectrum of the attenuated sample to be measured curve SND;

[0020] wherein the attenuation factor is the ratio of the peak intensity of the blank background curve B to the attenuated blank background curve BND.

[0021] In an embodiment of the first aspect, the attenuation factor is 1-100. Preferably, the attenuation factor is 1.2-50. More preferably, the attenuation factor is 1.2-1.8.

[0022] In an embodiment of the first aspect, in step S3, the attenuating the signal of the blank background comprises setting a neutral density attenuator on the light signal propagation path between the sample chamber and the detector when scanning the blank background in the first predetermined wavelength range.

[0023] In an embodiment of the first aspect, the neutral density attenuator has the same absorbance in the range of 300-800 nm.

[0024] In an embodiment of the first aspect, the sample to be measured is selected from one or more of the group consisting of weakly luminescent sample to be measured, moderately luminescent sample to be measured, and strongly luminescent sample to be measured.

[0025] In an embodiment of the first aspect, the sample to be measured is selected from one or more of the group consisting of quinine sulfate, YAGA crystal, and rhodamine 6G.

[0026] In an embodiment of the first aspect, during the measurement, the concentration of the sample to be measured is less than or equal to 1.0 x 10 -2 mol / L.

[0027] In the second aspect, the present application provides a measuring device for absolute quantum yield, comprising an excitation light source, a sample chamber for placing the sample to be measured, an integrating sphere, and a detector, and the measuring device further comprises a neutral density attenuator, which is set on the light signal propagation path between the sample chamber and the detector.

[0028] In an embodiment of the second aspect, the neutral density filter has the same absorbance in the range of 300-800 nm.

[0029] In an embodiment of the second aspect, the excitation light source is a xenon lamp or a laser.

[0030] Compared with the prior art, the positive effects of the present application are that the measurement method described herein can accurately determine the absolute quantum yield of the sample to be measured by setting a neutral density filter between the sample chamber and the detector without limiting the excitation light source, so that the signal falls within the linear response range of the detector. The measurement method described herein can be used to measure the absolute quantum yield of weakly luminescent samples to be measured and moderately luminescent samples to be measured. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Spectra curves of blank background and sample to be measured with and without neutral density filter.

[0032] Figure 2 is a schematic diagram of mathematical operation of the curve to obtain the absorption signal intensity and emission signal intensity of the sample to be measured.

[0033] Figure 3 Transmittance of different types of filters in the range of 300-800 nm, wherein figure a shows the transmittance of the filter of Haida Xingguang, and figure b shows the transmittance of the filter of Newport oriel.

[0034] Figure 4 A schematic diagram of the measuring device for absolute quantum yield is shown.

[0035] Figure 5 A measurement curve of rhodamine 6G with a concentration of 1.0 x 10 -6 mol / L is shown.

[0036] Figure 6 A difference spectrum of rhodamine 6G with a concentration of 1.0 x 10 -6 mol / L is shown.

[0037] Figure 7 A measurement curve of rhodamine 6G with a concentration of 1.0 x 10 -5 mol / L is shown.

[0038] Figure 8 A difference spectrum of rhodamine 6G with a concentration of 1.0 x 10 -5 mol / L is shown.

[0039] Figure 9 A measurement curve of rhodamine 6G with a concentration of 5.0 x 10 -5The measurement curve of rhodamine 6G with a concentration of 5.0 x 10

[0040] Figure 10 The measurement curve of rhodamine 6G with a concentration of 5.0 x 10 -5 The difference spectrum of rhodamine 6G with a concentration of 5.0 x 10

[0041] Figure 11 The measurement curve of fluorescein with a concentration of 1.0 x 10 -6

[0042] Figure 12 The difference spectrum of fluorescein with a concentration of 1.0 x 10 -6

[0043] Figure 13 The measurement curve of quinine sulfate with a concentration of 1.0 x 10 -6

[0044] Figure 14 The difference spectrum of quinine sulfate with a concentration of 1.0 x 10 -6

[0045] Figure 15 The measurement curve of YAGA crystal.

[0046] Figure 16 The difference spectrum of YAGA crystal.

[0047] Figure 17 The measurement curve of quinine sulfate with a concentration of 5.0 x 10 -5

[0048] Figure 18 The difference spectrum of quinine sulfate with a concentration of 5.0 x 10 -5

[0049] In the measurement curve spectrum, the characteristic peak intensity of B, S, BND and SND spectrum decreases in turn. In the difference spectrum, the characteristic peak with smaller peak width is BND-SND, and the characteristic peak with larger peak width is S-B. DETAILED DESCRIPTION

[0050] ​​​​​​Unless otherwise indicated, all parts and percentages are on a weight basis, and all measurements and tests are made at a temperature of 23 °C and a relative humidity of 50% unless otherwise indicated. All patents, patent applications, and publications identified are hereby incorporated by reference in their entirety, and their equivalents, if any, are also incorporated by reference. In the event that any definition set forth in this application contradicts any definition that can be found in the patent literature including issued patents, then this application controls.

[0051] Numerical ranges in this disclosure are approximations, and thus the endpoints of ranges are not to be understood as being precise figures. Unless otherwise indicated, each numerical range is intended to include every number between the lowest and highest value, including the lowest and highest values. For example, if a range is stated as 100% to 1000%, it is intended to include, and thus disclose, every possible combination of numbers between the lowest value and the highest value, e.g., 100, 101, 102, etc., and not just the precise ranges explicitly recited. For ranges including values less than 1 or including fractions of less than 1, it is intended that the lower number is 0.0001, 0.001, 0.01, or 0.1 as appropriate. For ranges including values less than 10, e.g., 1 to 5, it is intended that the lower number is 0.1 as appropriate. These are only examples of what is specifically intended, and all possible combinations of numerical values between the lowest value and the highest value are to be considered to be expressly stated in this application. It should also be noted that the terms "first", "second", or the like, are used herein merely to distinguish one element from another, and are not intended to designate a particular order or sequence.

[0052] With respect to chemical compounds, the singular forms "a", "an", and "the" include all isomeric forms, unless the specific forms are explicitly described. This applies similarly to the singular forms "first", "second", etc. Also, the use of "one" or "said" to describe a noun does not exclude the plural forms.

[0053] The terms "comprising", "including", "containing", and variations thereof do not exclude any other components, steps or integers from being present in the compositions, methods, or processes of the application, and the compositions, methods, or processes of the application can include any additional additives, adjuvants, or compounds, unless expressly disclosed otherwise. The term "consisting essentially of to exclude any other components, steps or integers not specifically disclosed or listed. The term "or" as used in the application refers to any one of the listed members, or any combination of the members.

[0054] Method of measurement

[0055] In one embodiment, the present application provides a method for measuring absolute quantum yield.

[0056] Because the weak luminescence sample emits a small part of signal, it is difficult to be directly detected, and the two-line method has a large error in measurement. Therefore, the emitted part of signal needs to be enhanced. In the process of fluorescence measurement, the methods for enhancing the signal include increasing the working voltage, adjusting the size of the slit, and increasing the concentration of the sample to be measured. However, these methods increase the absorption signal of the sample to be measured at the same time of increasing the fluorescence emission signal of the sample to be measured. In the process of quantum yield measurement, the existence of the linear response range of the detector requires that the absorption and emission signals cannot be enhanced at the same time.

[0057] The inventors of the present application first proposed a method for measuring four curves that can only enhance the emission signal, which is called four-line method (QY F ). The specific experimental process of the method for measuring absolute quantum yield of the present application is as follows: first, adjust the parameters of the spectral instrument to obtain a clear emission spectrum signal of the sample to be measured, scan to obtain the emission spectrum curve S of the sample to be measured; then replace the sample to be measured with a blank background, scan to obtain the blank background curve B; then place a neutral density filter between the sample chamber and the detector to make the blank background signal fall within the linear response range of the detector, at this time, obtain the attenuated blank background curve BND, replace the blank background with the sample to be measured to obtain the attenuated sample to be measured curve SND, and finally subtract the influence of the neutral density filter to calculate the quantum yield (QY Figure 1 ). This method is called four-line method. The data processing process can be seen in Figure 1 and Figure 2 , wherein Figure 1 shows the spectral curves of the blank background and the sample to be measured with and without the neutral density filter, Figure 2 is a schematic diagram of the curves after mathematical operation to obtain the absorption signal intensity and the emission signal intensity of the sample to be measured.

[0058] The absolute quantum yield calculation process is described as follows.

[0059] B refers to the blank background curve; BND refers to the blank background curve after adding the attenuator.

[0060] S refers to the emission spectrum curve of the sample to be measured; SND refers to the emission spectrum curve of the sample to be measured after adding the attenuator.

[0061] S-B refers to the difference spectrum between the emission spectrum curve of the sample to be measured and the blank background curve, and the area of the emission signal of the sample to be measured is A S-B .

[0062] SND-BND refers to the difference spectrum between the emission spectrum curve of the sample to be measured after adding the attenuator and the blank background curve, and the area of the emission signal of the sample to be measured after adding the attenuator is A SND-BND .

[0063] BND-SND refers to the difference spectrum between the blank background curve after adding the attenuator and the emission spectrum curve of the sample to be measured, and the area of the absorption signal of the sample to be measured is A BND-SND .

[0064] Let DB be the attenuation factor, and the value is equal to the ratio of the peak intensity of the blank background curve B and BND.

[0065] QY T = A SND-BND / A BND-SND (two-line method quantum yield calculation)

[0066] QY F = [A S-B / A BND-SND ] / DB (four-line method quantum yield calculation)

[0067] In the four-line method quantum yield calculation, the peak intensity of the emission spectrum curve S of the sample to be measured is within the linear response interval of the detector, and the emission part of the sample to be measured uses the difference spectrum S-B without adding the attenuator for area integration. In addition, the peak intensity of the blank background curve B without adding the attenuator exceeds the linear response interval of the detector, and the absorption part of the sample to be measured uses the difference spectrum BND-SND with the attenuator added for area integration. Finally, the influence of the attenuator is eliminated, and the absolute quantum yield of the sample to be measured is obtained.

[0068] The above process obtains the absolute quantum yield of the weak luminescence sample with single light source intensity. Next, a series of neutral density attenuators can be placed between the light source and the sample chamber to obtain corresponding different intensity excitation light sources. The four-line method measurement process is repeated, and finally data processing and calculation can obtain the light intensity dependent quantum yield of the weak luminescence sample to be measured.

[0069] The neutral density filter used in the present application requires the same absorbance in the range of 300-800 nm, such as Figure 3 Curve a cannot be used because it does not have the same absorbance in this interval, as shown by curve b.

[0070] Measuring device

[0071] In another embodiment, referring to Figure 4 The present application provides a measuring device for absolute quantum yield, comprising an excitation light source, a sample chamber for placing a sample to be measured, an integrating sphere, and a detector. The measuring device described herein further comprises a neutral density filter disposed on the light signal propagation path of the sample chamber and the detector. In a specific embodiment, along the propagation path of light, the measuring device for absolute quantum yield can comprise a light source, an excitation monochromator slit, an excitation lens, a sample cell integrating sphere, an emission lens, an emission monochromator slit, a detector, and a filter, wherein the filter is disposed between the emission lens and the emission monochromator slit.

[0072] In a specific embodiment, the neutral density filter has the same absorbance in the range of 300-800 nm. In a specific embodiment, the excitation light source can be selected from a small intensity light source such as a xenon lamp, or a high intensity light source such as a laser.

[0073] Example

[0074] The technical solutions of the present application will be described clearly and completely in combination with the embodiments of the present application. Unless otherwise specified, the reagents and raw materials used can be purchased through commercial channels. The experimental methods not specified in the following examples are selected according to conventional methods and conditions, or according to the product instructions.

[0075] In the following examples, the fluorescence spectrometer used is a high-level fluorescence steady-state transient measurement system (PTI Corporation, QM / TM / IM, USA).

[0076] Example 1

[0077] This example relates to the measurement of the absolute quantum yield of a weakly luminescent sample, Rhodamine 6G, using the four-line method.

[0078] The present application is mainly directed to the absolute quantum yield of weakly luminescent samples, which can significantly improve the accuracy of the measurement of the absolute quantum yield of such samples. Next, Rhodamine 6G solutions of different concentrations are used to simulate weakly luminescent, moderately luminescent, and strongly luminescent samples. The reason for choosing Rhodamine 6G is that this substance has stable luminescent properties, and when the concentration is less than 1.0 x 10 -2When the concentration of the rhodamine 6G solution is 5.0×10-5 mol / L, the quantum yield value does not change and is a fixed value 0.94. The absolute quantum yield is measured by using the two-line method and the four-line method respectively, and the calculation results are compared with the literature to investigate the testing effect of the two methods.

[0079] The steps of the embodiment are described as follows:

[0080] 1. A certain amount of rhodamine 6G is weighed and dissolved in ethanol to prepare three solutions with concentrations of 1.0×10-5 mol / L, 5.0×10-5 mol / L and 5.0×10-5 mol / L respectively; -6 -5 -5

[0081] 2. 2 mL of the rhodamine 6G ethanol solution is taken in a cuvette and placed in the integrating sphere in the sample chamber, 488 nm is used as the excitation wavelength, the size of the slit is adjusted until the emission signal can be obviously detected, and the sample emission spectrum curve S is obtained by scanning test;

[0082] 3. 2 ml of ethanol is taken in a cuvette and placed in the integrating sphere in the sample chamber, 488 nm is used as the excitation wavelength, and the background curve B is measured;

[0083] 4. A neutral density attenuation sheet (attenuation multiple 3.0) is placed between the sample chamber and the detector, the cuvette containing ethanol is placed in the integrating sphere, 488 nm is used as the excitation wavelength, and the attenuated background curve BND is measured, wherein the intensity of the Rayleigh peak of the light source is not higher than 1000000 (the linear response interval of the detector of the spectrometer used in the present application is 200000-1000000 counts);

[0084] 5. The ethanol is replaced with the rhodamine 6G solution in step (2), 488 nm is used as the excitation wavelength, and the attenuated sample emission spectrum curve SND is obtained.

[0085] The measurement curves of the rhodamine 6G with different concentrations obtained in Example 1 and the corresponding difference spectra are shown in Figures 5-10 .

[0086] Next, the quantum yield is calculated by using the two-line method and the four-line method respectively, and the results are shown in Table 1:

[0087] Table 1 Measurement of absolute quantum yield of rhodamine 6G by using the two-line method and the four-line method

[0088]

[0089] In Table 1, the full text of the literature 1 can be referred to Brower A M. Pure Appl. Chem., 2011, 83(12): 2213-2228. As can be seen from Table 1, when the concentration of the sample is 1.0×10-5 mol / L, the quantum yield value does not change and is a fixed value 0.94. The absolute quantum yield is measured by using the two-line method and the four-line method respectively, and the calculation results are compared with the literature to investigate the testing effect of the two methods. -6 ​​​mol / L, i.e. the weakly luminescent sample described herein, the average deviation of the test results of the two-line method reached 10.3%, which could not meet the test requirements. However, when the four-line method of the present application was used, the average deviation of the test results decreased to 0.3%. With the increase of the sample concentration, i.e. the medium-intensity and strongly luminescent samples described herein, the average deviation of the two-line method decreased significantly, and the four-line method increased slightly, but met the test requirement that the average deviation was less than 5.0%. Therefore, in the absolute quantum yield test, the two-line method is only applicable to medium-intensity and strongly luminescent samples, while the four-line method can cover weak, medium-intensity and strongly luminescent samples, and its advantage lies in greatly improving the measurement accuracy of the absolute quantum yield of weakly luminescent samples.

[0090] Next, the measurement of the sample light intensity-dependent absolute quantum yield will be described.

[0091] For example, the concentration of the rhodamine ethanol solution was 1.0 x 10 -5 mol / L, and the excitation wavelength was 350 nm. The measurement process and result calculation of the intensity-dependent quantum yield of the four-line method will be introduced.

[0092] A neutral density attenuation sheet (attenuation multiple 1.2) was placed between the light source and the sample chamber, and then steps 2, 3, 4 and 5 were repeated to obtain four curves of the sample emission spectrum and the background before and after attenuation. After data processing, the absolute quantum yield of the sample under the intensity of the light source was obtained.

[0093] The neutral density attenuation sheet between the excitation light source and the sample chamber was replaced (the attenuation multiple was changed, such as DB was 1.2, 1.5, 1.8, 2.4, 3.0, 3.5, 4.0, 10.0, 50.0, etc., which were all commercially available), and then the quantum yield of the four-line method under different light source intensities was tested, and the light source intensity-dependent absolute quantum yield of the sample was obtained.

[0094] Example 2

[0095] Next, the four-line method for measuring the absolute quantum yield of a weakly luminescent sample will be described. This example relates to the measurement of the absolute quantum yield of quinine sulfate and fluorescein with low concentrations.

[0096] The method described in the present application is mainly applied to the determination of the absolute quantum yield of weakly luminescent samples. Next, we will use it to determine the absolute quantum yield of quinine sulfate and fluorescein solutions with low concentrations. Quinine sulfate and fluorescein have stable luminescent properties and are often used as standard substances for relative quantum yield. The concentration of the measured sample was 1.0 x 10 -6 mol / L, which had a low luminescent intensity and could be regarded as a weakly luminescent sample. The excitation wavelengths were 350 nm and 460 nm, respectively. The concentration of sulfuric acid in the quinine sulfate solution was 0.1 mol / L, and the test steps were the same as those of rhodamine 6G. The measurement curve and difference spectrum of fluorescein obtained in Example 2 are shown in FIG. 2.Figure 11 and 12 The measurement curve and difference spectrum of the obtained quinine sulfate are shown in Figure 13 and 14 The calculation results are shown in Table 2.

[0097] Table 2 Measurement of absolute quantum yield of weakly luminescent samples by four-line method

[0098]

[0099] As shown in Table 2, the four-line method has high accuracy in the measurement of absolute quantum yield of dilute quinine sulfate and fluorescein solution. Therefore, the four-line method can be widely used in the measurement of absolute quantum yield of weakly luminescent samples, and can be used to solve the problem of absolute quantum yield measurement of solar cells, photocatalysis, luminescent materials and the like, and can be used to investigate the light intensity dependence.

[0100] Example 3

[0101] This example relates to the four-line method for measuring absolute quantum yield of moderately luminescent samples.

[0102] The method described in the present application is also applicable to the determination of absolute quantum yield of moderately luminescent samples, which is used in the determination of absolute quantum yield of YAGA crystal next. YAGA crystal is a commonly used wavelength calibration sample in a fluorescence spectrometer, which is a block solid and has moderate luminescent intensity. The measurement curve and difference spectrum of the YAGA crystal obtained in Example 3 are shown in Figure 15 and 16 respectively. The excitation wavelength is 352 nm, the standard quantum yield is 42%, and the absolute quantum yield of the YAGA crystal is measured by the four-line method as 42.3% with an average deviation of 0.7%.

[0103] The excitation wavelength in this example is 352 nm, and the attenuation factor of the neutral density attenuation sheet is 1.80.

[0104] Example 4

[0105] This example relates to the four-line method for measuring absolute quantum yield of strongly luminescent samples.

[0106] The method described in the present application is also applicable to the determination of absolute quantum yield of strongly luminescent samples, which is used in the determination of absolute quantum yield of quinine sulfate with high concentration next. The concentration of quinine sulfate is 5.0×10 -3 mol / L, the concentration of sulfuric acid in the solution is 0.5 mol / L, and it has strong fluorescence emission intensity, which is a strongly luminescent sample. The measurement curve and difference spectrum of the quinine sulfate obtained in Example 4 are shown in Figure 17 and 18 respectively. The excitation wavelength is 350 nm, the standard quantum yield is 52%, and the absolute quantum yield of the quinine sulfate is measured by the four-line method as 53.4% with an average deviation of 2.7%.

[0107] The excitation wavelength of this example was 350 nm, and the neutral density filter had an attenuation factor of 3.50.

[0108] The above description of the embodiments is to assist those of ordinary skill in the art to understand and apply the present application. Those skilled in the art can easily make various modifications to the embodiments and apply the general principles described herein to other embodiments without having to make creative efforts. Therefore, the present application is not limited to the embodiments described herein, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope and spirit of the present application are within the scope of the present application.

Claims

1. A method for measuring absolute quantum yield, characterized in that, The method includes the following steps: S1: When the emission signal of the sample to be tested can be directly detected by the detector, the sample to be tested is scanned within a first predetermined wavelength range to obtain the emission spectrum curve S of the sample to be tested. S2: Under the same detection conditions as in step S1, the sample to be tested is replaced with a blank background, and the blank background is scanned within a first predetermined wavelength range to obtain the blank background curve B; S3: Attenuate the signal of the blank background so that the intensity of the blank background signal falls within the linear response range of the instrument detector, scan the blank background within a first predetermined wavelength range, and obtain the attenuated blank background curve BND. S4: Under the same detection conditions as in step S3, replace the blank background with the sample to be tested, scan the sample to be tested within a first predetermined wavelength range, and obtain the attenuated sample curve SND; and, S5: Subtract the effect of attenuation to obtain the absolute quantum yield of the sample to be tested; In step S5, the subtraction of the effects of attenuation includes calculating the absolute quantum yield of the sample under test according to the following formula (1): QY F =[A S-B / A BND-SND ] / DB formula (1), Among them, QY F A represents the absolute quantum yield of the sample being tested. S-B A represents the area of ​​the spectrum integrating the emitted signal of the sample under test. BND-SND The area of ​​the spectrum representing the absorption signal of the sample under test is represented by DB, which represents the attenuation factor. Wherein, the spectrum of the emission signal of the sample to be tested is the spectrum obtained by subtracting the emission spectrum curve S of the sample to be tested from the blank background curve B. The spectrum of the absorption signal of the sample to be tested is obtained by subtracting the attenuated blank background curve BND and the attenuated sample curve SND. Wherein, the attenuation factor is the ratio of the peak intensity of the blank background curve B to the attenuated blank background curve BND.

2. The measurement method as described in claim 1, characterized in that, The attenuation factor is 1-100.

3. The measurement method as described in claim 2, characterized in that, The attenuation factor is 1.2-50.

4. The measurement method according to any one of claims 1-3, characterized in that, In step S3, the signal attenuation of the blank background includes setting a neutral density attenuator on the optical signal propagation path of the sample chamber and the detector when scanning the blank background within a first predetermined wavelength range.

5. The measurement method as described in claim 4, characterized in that, The neutral density attenuator has the same absorbance in the range of 300~800nm.

6. The measurement method according to any one of claims 1-2, characterized in that, The test sample is selected from one or more of the following groups: weak luminescence test sample, medium luminescence test sample, and strong luminescence test sample.

7. The measurement method as described in claim 4, characterized in that, The sample to be tested is selected from one or more of the following groups: quinine sulfate, YAGA crystals, and rhodamine 6G.

8. A measuring device for absolute quantum yield, comprising an excitation light source, a sample chamber for placing a sample to be measured, an integrating sphere, and a detector, characterized in that, The measurement device further includes a neutral density attenuator, which is placed on the optical signal propagation path between the sample chamber and the detector, using the measurement method according to any one of claims 1-7.

9. The apparatus for measuring absolute quantum yield as described in claim 8, characterized in that, The neutral density attenuator has the same absorbance in the range of 300~800nm.

10. The apparatus for measuring absolute quantum yield as described in claim 8, characterized in that, The excitation source is a xenon lamp or a laser.

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