Method and apparatus for fitting transient absorption spectroscopy dynamics

Abstract

The application relates to a fitting method and device for transient absorption spectrum dynamics, belonging to the field of time-resolved spectrum. The device comprises a spectrum acquisition module, a dispersion correction module, a dynamic fitting module and an upper computer. The spectrum acquisition module is used for acquiring transient absorption spectrum data under a preset time delay sequence, so that a transient absorption spectrum data matrix is obtained. The dispersion correction module is used for generating a corrected transient absorption spectrum data matrix. The dynamic fitting module uses the corrected transient absorption spectrum data matrix and a related dynamic fitting function to fit the characteristic constant of intrinsic excited state decay dynamics. The application describes the convolution of pump light, probe light and intrinsic spectrum dynamics through the time-domain representation and fitting of the pump light and the probe light, and obtains accurate intrinsic transient absorption dynamics through a fitting model, so that the fitting of transient absorption spectrum dynamics is realized. The application can eliminate the influence of the pulse width of the pump light and the probe light on the transient absorption spectrum dynamics, and improves the fitting precision.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of time-resolved spectroscopy, and particularly relates to a fitting method and device for transient absorption spectroscopy dynamics. BACKGROUND

[0002] The need for developing new optoelectronic materials requires in-depth research on the band structure of the material, carrier relaxation dynamics, interface carrier transfer and other processes. Transient absorption spectroscopy technology is an important tool for studying the above processes, especially non-radiative processes. Transient absorption spectroscopy uses a pump light to generate excited carriers in the sample to be measured, and then irradiates the sample with a probe light, and the relaxation dynamics of the excited carriers is characterized by the change in the absorption spectrum of the probe light. Since the pump light and the probe light both have a certain pulse width, they will continue to act on the sample, causing the rising edge of the signal or the falling edge of the rapid relaxation to have a measurement system error. The essence of this system error is the convolution of the pump light, the probe light and the intrinsic dynamics in the time domain. The above system error makes it impossible to accurately characterize the carrier dynamics process of the material with a short carrier relaxation time. In addition, under the existing circumstances, the time resolution of the transient absorption spectroscopy is mainly limited by the pulse width of the pump light and the probe light. In order to achieve high time resolution, the pulse width of the pump light and the probe light in the time domain usually needs to be compressed, which increases the overall equipment cost. SUMMARY

[0003] In order to solve the error of transient absorption spectroscopy in measuring the dynamics with a short relaxation time, the purpose of the application is to provide a fitting method and device for transient absorption spectroscopy dynamics, which describes the convolution of the pump light, the probe light and the intrinsic spectroscopy dynamics through the time domain characterization and fitting of the pump light and the probe light, and obtains accurate intrinsic transient absorption dynamics through the fitting model, thereby realizing the fitting of the transient absorption spectroscopy dynamics.

[0004] The purpose of the application is achieved by the following technical solutions:

[0005] The fitting method for transient absorption spectroscopy dynamics disclosed by the application comprises the following steps:

[0006] Step one, respectively characterize and fit the time domain characteristics of the pump light and the probe light to obtain the pulse time domain distribution characteristics of the pump light and the pulse time domain distribution characteristics of the probe light;

[0007] The time domain distribution of the pump light and the probe light is defined as the following formula:

[0008]

[0009] Wherein, i=1 represents the pump light, i=2 represents the probe light; t represents time, T iFull width at half maximum of the pulsed laser; C i is a constant, obtained by formula (2):

[0010]

[0011] The pulse time-domain distribution characteristics of the obtained pump light or the pulse time-domain distribution characteristics of the probe light are fitted by formula (1) and formula (2), and the full width at half maximum T1 and T2 of the pump light and the probe light are obtained by normalized fitting;

[0012] Step two, the time delay sequence with M increasing elements is T M ={t1,t2,t3,...,t k-1 ,t k ,t k+1 ,...,t M}; Wherein, tk-tk-1=tk-1-tk-2=...=t2-t1=p, that is, the increasing time delay subsequence TZ k ={t1,t2,...t k-1 ,t k} adopts a linear distribution strategy, the interval length is p, and the maximum value of the interval length satisfies:

[0013] Further, for the increasing time delay subsequence TZM k ={t k+1 ,t k+2 ,...,t M-1 ,t M}, a linear distribution or an exponential distribution or other distribution strategy is adopted.

[0014] Step three, according to the delay sequence T M Collect transient absorption spectrum data under different time delays to form an M-row-by-N-column transient absorption spectrum data matrix:

[0015]

[0016] Wherein a ij represents the transient absorption data of the jth wavelength value under the ith time delay;

[0017] At the same time, a wavelength vector composed of N wavelength values is obtained:

[0018]

[0019] Step four, generate the corrected transient absorption spectrum data matrix A', including:

[0020] The dispersion correction function f(w) is determined based on the optical path characteristics of the transient absorption spectrometer and the characteristics of the sample, where w is the wavelength value;

[0021] The dispersion correction function takes the form of an R-degree polynomial function, where n represents a polynomial term of degree n, and c n The fitting constant representing the term n:

[0022]

[0023] Extract each column vector of matrix A from step three. The dynamic data at the q-th wavelength are used for the following operations:

[0024] Using the dispersion correction function of equation (3), based on the increasing time delay sequence T M Generate a new interval segmentation sequence:

[0025] S M ={t1-f(w q ),t2-f(w q ),...,t M-1 -f(w q ),t M -f(w q )}, where w q It is the q-th wavelength value;

[0026] According to S M The correction interpolation function g at the q-th wavelength q (t), representing wavelength w q Dispersion-corrected transient absorption kinetics data at time t:

[0027] Case 1: Correction interpolation function g q (t) is a linear interpolation model that must satisfy:

[0028]

[0029] Case 2: Correction interpolation function g q (t) represents a nonlinear interpolation model that must satisfy:

[0030]

[0031] Among them, L j (t) is called the basic nonlinear interpolation function, which must satisfy:

[0032]

[0033] Based on the correction interpolation function g q (t) Generates a column vector of corrected dynamic data at the q-th wavelength.

[0034] generating a corrected transient absorption spectrum data matrix

[0035] Step five, the column vector of the corrected kinetic data at the qth wavelength obtained in step four Carrying out intrinsic spectral kinetic fitting, obtaining an accurate transient absorption spectral kinetic equation, and realizing the fitting of the transient absorption spectral kinetics.

[0036] The following kinetic fitting function is used for kinetic fitting:

[0037]

[0038] Wherein, ΔA(t) represents the transient absorption kinetic data at time t, D(t) represents the intrinsic excited state decay kinetic function of the sample to be tested, and is expressed as:

[0039]

[0040] Wherein, d0 is a constant, U represents the number of components, t0 is used for correcting the time zero point, τ i is the characteristic time constant of the ith exponential decay component, B i is the characteristic intensity constant of the ith exponential decay component.

[0041] The column vector of the corrected kinetic data at the qth wavelength is selected from the corrected transient absorption spectrum data matrix, numerical fitting is carried out using the kinetic fitting function, the related parameters of the intrinsic excited state decay kinetic function D(t) are obtained, the convolution of the pump light, the probe light and the intrinsic spectral kinetics is decoupled, the characteristic constants of the intrinsic excited state decay kinetics are fitted, and thus the accurate transient absorption spectral kinetics is obtained, that is, the fitting of the transient absorption spectral kinetics is realized.

[0042] The transient absorption spectral kinetics device disclosed in the application is used for realizing the fitting method of the transient absorption spectral kinetics. The transient absorption spectral kinetics device comprises a spectrum acquisition module, a dispersion correction module, a kinetic fitting module and an upper computer.

[0043] The spectrum acquisition module is used for acquiring the transient absorption spectral data under a preset increasing time delay sequence, and obtaining a transient absorption spectral data matrix.

[0044] The dispersion correction module is used for generating a corrected transient absorption spectrum data matrix.

[0045] The kinetic fitting module is used for fitting the characteristic constants of the intrinsic excited state decay kinetics by using the corrected transient absorption spectrum data matrix and the involved kinetic fitting function.

[0046] The host computer is used to control the work of the spectrum acquisition module, the dispersion correction module and the kinetics fitting module, display the test results, and realize the human-computer interaction function.

[0047] Further, the spectrum acquisition module includes femtosecond laser generated by the femtosecond laser generator is divided into pump light and probe light through the first beam splitter; the probe light enters the optical delay line, and then enters the supercontinuum white light generation module to generate supercontinuum white light, which is collected by the spectrometer after passing through the sample to be measured; the pump light passes through the laser frequency domain shaping module to generate adjustable frequency femtosecond laser, and then is irradiated on the sample to be measured through the optical switch, and the spots of the pump light and the probe light are spatially coincided on the sample to be measured; the electrical control module is used to control the working time sequence of the optical switch and the spectrometer, and communicates with the spectrometer, and transmits the transient absorption spectrum data matrix obtained by digital-to-analog conversion to the dispersion correction module;

[0048] The dispersion correction module receives the transient absorption spectrum data matrix, corrects the dispersion of the transient absorption spectrum data matrix, and then transmits the corrected transient absorption spectrum data matrix to the kinetics fitting module;

[0049] The kinetics fitting module includes a first pulse width analysis module and a second pulse width analysis module; the pump light enters the first pulse width analysis module through the second beam splitter, and the probe light enters the second pulse width analysis module through the third beam splitter; the first pulse width analysis module and the second pulse width analysis module analyze the time domain characteristics of the pump light and the probe light, and realize the function of transient absorption spectrum kinetics fitting in combination with the corrected transient absorption spectrum data matrix.

[0050] Further, the spectrum acquisition module includes pump light generated by the pump laser irradiating on the sample to be measured; the supercontinuum white light emitted by the probe laser is divided into two parts through the first beam splitter, one part is collected by the first spectrometer after passing through the sample to be measured, and the other part is collected by the second spectrometer; the electrical control module receives the synchronous output signal of the pump laser, and triggers the probe laser in an external triggering manner after a certain time delay, so as to generate a preset time delay of the pump light and the probe light; the data communication module communicates with the first spectrometer and the second spectrometer, and transmits the transient absorption spectrum data matrix obtained by digital-to-analog conversion to the dispersion correction module;

[0051] The dispersion correction module receives the transient absorption spectrum data matrix, corrects the dispersion of the transient absorption spectrum data matrix, and then transmits the corrected transient absorption spectrum data matrix to the kinetics fitting module;

[0052] The kinetic fitting module comprises a first pulse width analysis module and a second pulse width analysis module; the pump light enters the first pulse width analysis module through a beam splitter, and the probe light enters the second pulse width analysis module through the beam splitter; the first pulse width analysis module and the second pulse width analysis module analyze the time-domain characteristics of the pump light and the probe light, and realize the function of transient absorption spectrum kinetic fitting in combination with the corrected transient absorption spectrum data matrix.

[0053] Beneficial effects:

[0054] 1. The transient absorption spectrum kinetic fitting method and device disclosed by the application, through time-domain representation and fitting of pump light and probe light, convolution of pump light, probe light and intrinsic spectrum kinetics, and through a fitting model, accurate intrinsic transient absorption kinetics is obtained, the influence of pump light and probe light pulse width on transient absorption spectrum kinetics is eliminated, system error is eliminated, and thus accurate intrinsic transient absorption spectrum kinetics is obtained, which is of great significance for characterization of photo-physical and photo-chemical properties of photoelectric materials with short carrier relaxation time.

[0055] 2. The transient absorption spectrum kinetic fitting method and device disclosed by the application, through convolution of pump light, probe light and intrinsic spectrum kinetics, the influence of pump light and probe light pulse width on transient absorption spectrum kinetics is eliminated, system error is eliminated, and intrinsic transient absorption spectrum kinetics can be decoupled when the carrier relaxation time is shorter than the laser pulse width.

[0056] 3. The transient absorption spectrum kinetic fitting method and device disclosed by the application, through convolution of pump light, probe light and intrinsic spectrum kinetics, the influence of pump light and probe light pulse width on transient absorption spectrum kinetics is eliminated, system error is eliminated, the requirement of pulse width of a pump laser or a probe laser in transient absorption spectrum can be reduced, and a laser with long laser pulse width can also be applied to transient absorption spectrum, the device can maintain high time resolution, and the overall cost of the device can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort.

[0058] Figure 1 is a flowchart of a transient absorption spectrum kinetic fitting method provided by the embodiment of the application.

[0059] Figure 2Fig. 1 is a schematic diagram of a first transient absorption spectrum dynamics fitting principle according to an embodiment of the present application.

[0060] Figure 3 Fig. 2 is a schematic diagram of a second transient absorption spectrum dynamics fitting principle according to an embodiment of the present application.

[0061] Figure 2 The parts in Fig. 1 are explained as follows: 1 - femtosecond laser; 2 - laser frequency domain shaping module; 3 - optical delay line; 4 - supercontinuum white light generation module; 5 - sample to be measured; 6 - optical switch; 7 - spectrometer; 8 - electrical control module; 9 - dispersion correction module; 10 - dynamics fitting module; 11 - first pulse width analysis module; 12 - second pulse width analysis module; 13 - first beam splitter; 14 - second beam splitter; 15 - host computer;

[0062] Figure 3 The parts in Fig. 2 are explained as follows: 16 - pump laser; 17 - probe laser; 18 - sample to be measured; 19 - first spectrometer; 20 - second spectrometer; 21 - first beam splitter; 22 - second beam splitter; 23 - third beam splitter; 24 - first pulse width analysis module; 25 - second pulse width analysis module; 26 - time interval analysis module; 27 - data communication module; 29 - dispersion correction module; 30 - dynamics fitting module; 31 - host computer. DETAILED DESCRIPTION

[0063] In order to make the personnel in the art better understand the present application scheme, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by the personnel in the art without making creative efforts should belong to the protection scope of the present application.

[0064] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0065] Embodiment 1:

[0066] Figure 2 This is a schematic diagram illustrating the principle of the first transient absorption spectrum dynamic fitting method according to an embodiment of the present invention. This method is generally used when the time resolution of the transient absorption spectrum is required to be on the order of femtoseconds and the detection time window is on the order of nanoseconds. Figure 2 As shown, the femtosecond laser generated by femtosecond laser 1 is split into pump light and probe light by beam splitter 13. After the probe light is split by beam splitter 14, part of the probe light enters the second pulse width analysis module 12, and the other part enters the optical delay line 3, and then enters the supercontinuum white light generation module 4 to generate supercontinuum white light, which is collected by the spectrum acquisition module 7 after passing through the sample 5. The pump light is generated by laser frequency domain shaping module 2 to generate frequency-tunable femtosecond laser, and then passes through optical switch 6. After passing through beam splitter 15, part of the pump light enters the first pulse width analysis module 11, and the other part of the pump light illuminates the sample 5. The light spots of the pump light and probe light are... The samples overlap; the electrical control module 8 controls the working timing of the optical switch 6 and the spectrometer 7, and communicates with the spectrometer 7 to transmit the transient absorption spectrum data matrix obtained by digital-to-analog conversion to the dispersion correction module 9; the dispersion correction module 9 transmits the corrected transient absorption spectrum data matrix to the dynamics fitting module 10; the host computer 14 communicates with the dynamics fitting module 10 and realizes interaction with the user; the first pulse width analysis module 11 and the second pulse width analysis module 12 analyze the temporal characteristics of the pump light and the probe light, and transmit the above temporal characteristics to the dynamics fitting module 10 to realize the function of transient absorption spectrum dynamics fitting.

[0067] The dynamic fitting method for transient absorption spectra based on this embodiment is implemented in the following steps:

[0068] S10. Temporal characterization and fitting of pump and probe beams;

[0069] The temporal characteristics of the pump light and the probe light are characterized and fitted respectively to obtain the pulse temporal distribution characteristics of the pump light and the pulse temporal distribution characteristics of the probe light.

[0070] The temporal distribution of the pump light and probe light is defined by the following formula:

[0071]

[0072] Where i=1 represents the pump light, and i=2 represents the probe light; t represents time, T i Used to characterize the full width at half maximum (FWHM) of a pulsed laser; C i It is a constant, obtained through the following formula:

[0073]

[0074] The pulse time-domain distribution characteristics of the obtained pump light or the pulse time-domain distribution characteristics of the probe light are fitted by using formula (9) and formula (10), and the full width at half maximum T1 and T2 of the pump light and the probe light are obtained by normalization fitting;

[0075] The first pulse width analysis module and the second pulse width analysis module can be selected from a self-coherence instrument, so as to characterize and analyze the time-domain characteristics of the pump light and the probe light with a time resolution of femtosecond level.

[0076] S11. A time delay sequence is set;

[0077] The time delay sequence of the femtosecond transient absorption spectrum is determined by the host computer. The preset increasing time delay sequence T M = {t1, t2, t3,..., t k-1 , t k , t k+1 ,..., t M}. Wherein, tk-tk-1=tk-1-tk-2=...=t2-t1=p, that is, the increasing time delay sub-sequence TZ k = {t1, t2,..., t k-1 , t k} adopts a linear distribution strategy, and the interval length is p, and the maximum value of the interval length satisfies the following conditional restriction: For example, considering the case that the laser pulse width emitted by the femtosecond laser is 0.2 ps, the interval length p is set to 0.04 ps; the increasing time delay sub-sequence TZ is set to -1 ps, -0.96 ps, -0.92 ps, …, 0.92 ps, 0.96 ps, 1 ps; the position of the optical delay line 3 is controlled by the host computer 14, so as to adjust the optical path difference of the pump light and the probe light.

[0078] For the increasing time delay sub-sequence TZM k = {t k , t k+1 ,..., t M-1 , t M}, linear distribution or exponential distribution is adopted. For example, the increasing time delay sub-sequence TZM k is 2 ps, 4 ps, 6 ps, …, 96 ps, 98 ps, 100 ps.

[0079] S12. The transient absorption spectrum data under the preset time delay sequence is sequentially collected;

[0080] The transient absorption spectrum data under different time delays is collected according to the delay sequence T M , and an M-row-by-N-column transient absorption spectrum data matrix is formed:

[0081]

[0082] Where a ij This represents the transient absorption data for the j-th wavelength value at the i-th time delay.

[0083] Simultaneously obtain a wavelength vector composed of N wavelength values:

[0084]

[0085] S13. Generate the corrected transient absorption spectrum data matrix;

[0086] The dispersion correction function f(w) is determined based on the optical path characteristics of the transient absorption spectrometer and the characteristics of the sample, where w is the wavelength value;

[0087] The dispersion correction function takes the form of an R-degree polynomial function, where n represents a polynomial term of degree n, and c n The fitting constant representing the term n:

[0088]

[0089] Extract each column vector of matrix A from step three. The dynamic data at the q-th wavelength are used for the following operations:

[0090] Using the dispersion correction function of equation (11), based on the increasing time delay sequence T M Generate a new interval segmentation sequence:

[0091] S M ={t1-f(w q ),t2-f(w q ),...,t M-1 -f(w q ),t M -f(w q )}, where w q It is the q-th wavelength value;

[0092] According to S M The correction interpolation function g at the q-th wavelength q (t), representing wavelength w q Dispersion-corrected transient absorption kinetics data at time t:

[0093] Case 1: Correction interpolation function g q (t) is a linear interpolation model that must satisfy:

[0094]

[0095] Case II, correction of the interpolation function g q (t) is a nonlinear interpolation model, which satisfies:

[0096]

[0097] where L j (t) is called the basic nonlinear interpolation function, which satisfies:

[0098]

[0099] According to the correction interpolation function g q (t) to generate the corrected kinetic data column vector at the qth wavelength

[0100]

[0101] Generate the corrected transient absorption spectrum data matrix

[0102] S14. Eigen spectrum kinetic fitting;

[0103] Eigen spectrum kinetic fitting is performed on the corrected kinetic data column vector at the qth wavelength obtained in step four to obtain the accurate transient absorption spectrum kinetics.

[0104] The following kinetic fitting function is used for kinetic fitting:

[0105]

[0106] where ΔA(t) represents the transient absorption kinetic data at time t, D(t) represents the eigen excited state decay kinetic function of the sample to be tested, and is expressed as:

[0107]

[0108] where d0 is a constant, U represents the number of components, t0 is used to correct the time zero point, τ i is the characteristic time constant of the ith exponential decay component, and B i is the characteristic intensity constant of the ith exponential decay component.

[0109] The corrected kinetic data column vector at the qth wavelength is selected from the corrected kinetic data column vector at the qth wavelength, and the kinetic fitting function is used for numerical fitting to obtain the related parameters of the eigen excited state decay kinetic function D(t), the convolution of the pump light, the probe light and the eigen spectrum kinetics is decoupled, the characteristic constant of the eigen excited state decay kinetics is fitted, and thus the accurate transient absorption spectrum kinetics is obtained.

[0110] Embodiment 2

[0111] Figure 3 is a schematic diagram of the principle of transient absorption spectrum kinetics fitting according to an embodiment of the present application. This scheme is generally adopted when the time resolution requirement of transient absorption spectrum is in the sub-nanosecond to nanosecond order, and the detection time window is in the microsecond to millisecond order. As shown in Figure 3 , the pump light generated by the pump laser 16 irradiates on the sample 18 to be measured; the supercontinuum white light emitted by the probe laser 17 is used as the probe light, which is divided into two parts by the first beam splitter 22, one part is transmitted through the sample 18 to be measured and collected by the first spectrometer 19, and the other part is collected by the second spectrometer 20; the electrical control module 27 receives the synchronization output signal of the pump laser 16, and triggers the probe laser 17 in an external triggering manner after a certain time delay, so as to generate a preset time delay of the pump light and the probe light; the time domain characteristics of the pump light and the probe light are characterized by the first pulse width analysis module 24 and the second pulse width analysis module 25 respectively, and are sent to the time interval analysis module 16 for analyzing the actual time delay of the pump light and the probe light; the above data are sent to the data communication module 28; in addition, the data communication module 28 also communicates with the first spectrometer 19 and the second spectrometer 20, obtains the transient absorption spectrum matrix, and sends it to the dispersion correction module 29; the dispersion correction module 29 transmits the corrected transient absorption spectrum data matrix to the kinetics fitting module 30 to realize the function of kinetics fitting; the upper computer 31 communicates with the kinetics fitting module 30, and realizes the interaction with the user.

[0112] The transient absorption spectrum kinetics fitting method based on the embodiment is specifically implemented as follows:

[0113] S10. Time domain characterization and fitting of pump light and probe light;

[0114] The time domain characteristics of the pump light and the probe light are characterized and fitted respectively to obtain the pulse time domain distribution characteristics of the pump light and the probe light;

[0115] The time domain distribution of the pump light and the probe light is defined as the following formula:

[0116]

[0117] Wherein, i=1 represents the pump light, and i=2 represents the probe light; t represents time, T i is used to characterize the full width at half maximum of the pulse laser; C i is a constant, which is obtained by the following formula:

[0118]

[0119] The pulse time-domain distribution characteristics of the obtained pump light or probe light are fitted by using formula (17) and formula (18), and the full width at half maximum T1 and T2 of the pump light and the probe light are obtained by normalization fitting;

[0120] The first pulse width analysis module and the second pulse width analysis module can select a high-speed photoelectric detector (bandwidth greater than 2GHz), so as to characterize and analyze the time-domain characteristics of the pump light and the probe light with a time resolution of picoseconds.

[0121] S11. Set a time delay sequence;

[0122] The time delay sequence of the nanosecond transient absorption spectrum is determined by the host computer. The preset increasing time delay sequence T M ={t1,t2,t3,...,t k-1 ,t k ,t k+1 ,...,t M} has M elements. Wherein, tk-tk-1=tk-1-tk-2=...=t2-t1=p, that is, the increasing time delay subsequence TZ k ={t1,t2,...t k-1 ,t k} adopts a linear distribution strategy, and the interval length is p, and the maximum value of the interval length satisfies the following conditional restriction: For example, the time delay sequence of the nanosecond transient absorption spectrum is determined by the host computer. Considering that the laser pulse width emitted by the nanosecond laser is 1ns, the interval length p is set to 0.2ns; the increasing time delay subsequence TZ is set to -3ns, -2.8ns, …, 2.8ns, 3ns;

[0123] For the increasing time delay subsequence TZM k ={t k ,t k+1 ,...t M-1 ,t M}, a linear distribution or an exponential distribution or other distribution strategy is adopted. For example, the increasing time delay subsequence TZM k is 4ns, 6ns, 8ns, …, 96ns, 98ns, 100ns.

[0124] S12. Collect transient absorption spectrum data under the preset time delay sequence in turn;

[0125] According to the delay sequence T M , the transient absorption spectrum data under different time delays are collected, and an M-row-by-N-column transient absorption spectrum data matrix is formed:

[0126]

[0127] Where a ij This represents the transient absorption data for the j-th wavelength value at the i-th time delay.

[0128] Simultaneously obtain a wavelength vector composed of N wavelength values:

[0129]

[0130] S13. Generate the corrected transient absorption spectrum data matrix;

[0131] The dispersion correction function f(w) is determined based on the optical path characteristics of the transient absorption spectrometer and the characteristics of the sample, where w is the wavelength value;

[0132] The dispersion correction function takes the form of an R-degree polynomial function, where n represents a polynomial term of degree n, and c n The fitting constant representing the term n:

[0133]

[0134] Extract each column vector of matrix A from step three. The dynamic data at the q-th wavelength are used for the following operations:

[0135] Using the dispersion correction function of equation (19), based on the increasing time delay sequence T M Generate a new interval segmentation sequence:

[0136] S M ={t1-f(w q ),t2-f(w q ),...,t M-1 -f(w q ),t M -f(w q )}, where w q It is the q-th wavelength value;

[0137] According to S M The correction interpolation function g at the q-th wavelength q (t), representing wavelength w q Dispersion-corrected transient absorption kinetics data at time t:

[0138] Case 1: Correction interpolation function g q (t) is a linear interpolation model that must satisfy:

[0139]

[0140] Case 2: Correction interpolation function gq (t) is a nonlinear interpolation model, which satisfies:

[0141]

[0142] where L j (t) is called a basic nonlinear interpolation function, which satisfies:

[0143]

[0144] The column vector of corrected kinetic data at the qth wavelength is generated according to the corrected interpolation function gq(t)

[0145]

[0146] The corrected transient absorption spectrum data matrix is generated

[0147] S14. Eigen spectrum kinetic fitting;

[0148] The column vector of corrected kinetic data at the qth wavelength obtained in step four is selected Eigen spectrum kinetic fitting is performed to obtain accurate transient absorption spectrum kinetics.

[0149] The following kinetic fitting function is used for kinetic fitting:

[0150]

[0151] where ΔA(t) represents the transient absorption kinetic data at time t, D(t) represents the eigen excited state decay kinetic function of the sample to be tested, and is expressed as:

[0152]

[0153] where d0 is a constant, U represents the number of components, t0 is used for correcting the time zero point, τ i is the characteristic time constant of the ith exponential decay component, B i is the characteristic intensity constant of the ith exponential decay component;

[0154] The column vector of corrected kinetic data at the qth wavelength is selected, numerical fitting is performed using the kinetic fitting function, the related parameters of the eigen excited state decay kinetic function D(t) are obtained, the convolution of the pump light, the probe light and the eigen spectrum kinetics is decoupled, the characteristic constants of the eigen excited state decay kinetics are fitted, and thus accurate transient absorption spectrum kinetics is obtained.

[0155] The above detailed description of the specific description, the purpose, technical scheme and beneficial effects of the application are further described in detail, it should be understood that the above description is only a specific embodiment of the application, and is not used to limit the protection scope of the application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A method of fitting transient absorption spectroscopy dynamics, characterized by: The method comprises the following steps, Step one, respectively characterizing and fitting the time domain characteristics of the pump light and the probe light, to obtain the pulse time domain distribution characteristics of the pump light and the pulse time domain distribution characteristics of the probe light; The time domain distribution of the pump light and the probe light is defined as the following formula: where i = 1 represents the pump light, i = 2 represents the probe light; t represents time, τ i is a constant, obtained by equation (2): i is a constant, obtained by equation (2): The obtained pulse time domain distribution characteristics of the pump light or the pulse time domain distribution characteristics of the probe light are fitted by using formula (1) and formula (2), and the full width at half maximum τ1 and τ2 of the pump light and the probe light are obtained by normalized fitting; Step two, the time delay sequence with M increasing elements is T M = {t1, t2, t3,..., t k-1 k k+1 ..., t M} ; wherein, t k -t k-1 = t k-1 -t k-2 =... = t2-t1 = p, that is, the increasing time delay sub-sequence TZ k = {t1, t2,..., t k-1 k} takes the linear distribution strategy, the interval length is p, and the maximum value of the interval length satisfies: ​​​ Step three, based on the delay sequence T M The transient absorption spectral data at different time delays are collected to form a matrix of transient absorption spectral data of M rows and N columns: where a ij represents the transient absorption data at the jth wavelength value at the ith time delay; At the same time, a wavelength vector composed of N wavelength values is obtained: Step four, generating a corrected transient absorption spectrum data matrix A', comprising: A dispersion correction function f(w) is determined according to the optical path characteristics of the transient absorption spectrometer and the sample characteristics, wherein w is the wavelength value; The dispersion correction function adopts the form of an Rth order polynomial function, n represents a polynomial term of n order, c n fitting constant of the term of n order extracting each column vector of the matrix A of step three representing the kinetic data at the qth wavelength, the following operations are performed: Using the dispersion correction function of formula (3), a sequence of increasing time delays T M generating a new interval division sequence: S M = {t1-f(w q ),t2-f(w q ),...,t M-1 -f(w q ),t M -f(w q )}, where w q is the qth wavelength value; According to S M The corrected interpolation function g q (t), represents the transient absorption kinetic data at wavelength w q The dispersion-corrected transient absorption kinetic data at time t: Case 1, correcting the interpolation function g q (t) is a model of linear interpolation, satisfying: Case 2, Correction of the Interpolation Function g q (t) is a model of the non-linear interpolation satisfying: where L j (t) is called the basic non-linear interpolation function and must satisfy: According to the correction interpolation function g q (t) generating a column vector of corrected kinetic data at the qth wavelength Generating corrected transient absorption spectral data matrices Step five, the column vector of the corrected kinetic data at the qth wavelength obtained in step four The intrinsic spectral kinetic fitting is performed to obtain an accurate transient absorption spectral kinetic equation, and the transient absorption spectral kinetic fitting is realized. The following kinetic fitting function is used for kinetic fitting: Wherein ΔA(t) represents the transient absorption kinetic data at time t, D(t) represents the intrinsic excited state decay kinetic function of the sample to be tested, and is expressed as: where d0 is a constant, U represents the number of components, t0 is used to correct the time zero point, τ i is the characteristic time constant of the i-th exponentially decaying component, B i is the characteristic intensity constant of the i-th exponentially decaying component; The column vector of the corrected kinetic data at the qth wavelength is selected from the corrected transient absorption spectrum data matrix A', and the kinetic fitting function is used for numerical fitting to obtain the related parameters of the intrinsic excited state decay kinetic function D(t), the convolution of the pump light, the probe light and the intrinsic spectral kinetics is decoupled, the characteristic constant of the intrinsic excited state decay kinetics is fitted, and the accurate transient absorption spectrum kinetics is obtained, that is, the fitting of the transient absorption spectrum kinetics is realized.

2. The method of fitting transient absorption spectroscopy dynamics of claim 1, wherein: In step two, for the increasing time delay sub-sequence TZM k = {t k+1 , t k+2 ,..., t M-1 , t M} takes a linear distribution or an exponential distribution.

3. Apparatus for fitting transient absorption spectroscopy dynamics for implementing the method according to claim 1 or 2, characterized in that: The device comprises a spectrum acquisition module, a dispersion correction module, a kinetic fitting module and an upper computer; The spectrum acquisition module is used for acquiring transient absorption spectrum data under a preset increasing time delay sequence to obtain a transient absorption spectrum data matrix; The dispersion correction module is used for generating a corrected transient absorption spectrum data matrix; The kinetic fitting module is used for fitting the corrected transient absorption spectrum data matrix and the related kinetic fitting function to obtain the characteristic constant of the intrinsic excited state decay kinetics; The upper computer is used for controlling the work of the spectrum acquisition module, the dispersion correction module and the kinetic fitting module, displaying the test results and realizing the human-computer interaction function.

4. The device of claim 3, wherein: The spectrum acquisition module comprises femtosecond laser generated by a femtosecond laser, which is divided into pump light and probe light by a first beam splitter; the probe light enters an optical delay line and then enters an ultrashort white light generation module to generate ultrashort white light, which is collected by a spectrometer after passing through the sample to be tested; the pump light passes through a laser frequency domain shaping module to generate adjustable frequency femtosecond laser, which then irradiates on the sample to be tested through an optical switch; the spots of the pump light and the probe light are spatially overlapped on the sample to be tested; an electrical control module is used for controlling the working time sequence of the optical switch and the spectrometer, and communicating with the spectrometer to transmit the transient absorption spectrum data matrix obtained by digital-to-analog conversion to the dispersion correction module; The dispersion correction module receives the transient absorption spectrum data matrix, performs dispersion correction thereon, and then transmits the corrected transient absorption spectrum data matrix to the kinetic fitting module; The kinetic fitting module comprises a first pulse width analysis module and a second pulse width analysis module; the pump light enters the first pulse width analysis module through a second beam splitter, and the probe light enters the second pulse width analysis module through a third beam splitter; the first pulse width analysis module and the second pulse width analysis module analyze the time-domain characteristics of the pump light and the probe light, and realize the function of transient absorption spectrum kinetic fitting in combination with the corrected transient absorption spectrum data matrix.

5. The apparatus of claim 3, wherein: The spectrum acquisition module comprises pump light generated by a pump laser and irradiated on a sample to be measured; supercontinuum white light emitted by a probe laser as probe light is divided into two parts by a first beam splitter, one part is collected by a first spectrometer after transmitting through the sample to be measured, and the other part is collected by a second spectrometer; the electrical control module receives a synchronous output signal of the pump laser, and triggers the probe laser in an external triggering manner after a certain time delay, so as to generate a preset time delay of the pump light and the probe light; the data communication module communicates with the first spectrometer and the second spectrometer, and transmits the transient absorption spectrum data matrix obtained by digital-to-analog conversion to the dispersion correction module; The dispersion correction module receives the transient absorption spectrum data matrix, performs dispersion correction on the transient absorption spectrum data matrix, and then transmits the corrected transient absorption spectrum data matrix to the kinetic fitting module; The kinetic fitting module comprises a first pulse width analysis module and a second pulse width analysis module; the pump light enters the first pulse width analysis module through a second beam splitter, and the probe light enters the second pulse width analysis module through a third beam splitter; the first pulse width analysis module and the second pulse width analysis module analyze the time-domain characteristics of the pump light and the probe light, and realize the function of transient absorption spectrum kinetic fitting in combination with the corrected transient absorption spectrum data matrix.

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