Transient absorption spectrum kinetics fitting method and device

Abstract

The invention discloses a fitting method and device of transient absorption spectroscopy, and belongs to the field of time-resolved spectroscopy. 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 incremental 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. And the dynamic fitting module is used for fitting the corrected transient absorption spectrum data matrix and a related dynamic fitting function to obtain a characteristic constant of the intrinsic excited state attenuation dynamics. Through time domain characterization and fitting of the pump light and the probe light, convolution of the pump light, the probe light and intrinsic spectrum dynamics is described, accurate intrinsic transient absorption dynamics is obtained through a fitting model, and fitting of transient absorption spectrum dynamics is achieved. According to the invention, the influence of the pulse width of the pump light and the probe light on transient absorption spectrum dynamics can be eliminated, and the fitting precision is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of time-resolved spectroscopy, and in particular relates to a fitting method and device for transient absorption spectral dynamics. Background Art

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

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

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] The transient absorption spectrum dynamics fitting method disclosed in the present invention comprises the following steps:

[0006] Step 1: characterize and fit the time domain characteristics of the pump light and the detection light respectively to obtain the pulse time domain distribution characteristics of the pump light and the pulse time domain distribution characteristics of the detection light;

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

[0008]

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

[0010]

[0011] 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 equations (1) and (2), and the full width at half maximum T of the pump light and the probe light are obtained by normalized fitting. 1 , T 2 ;

[0012] Step 2: The time delay sequence with M increasing elements is T M ={t 1 ,t 2 ,t 3 ,...,t k-1 ,t k ,t k+1 ,...,t M}; Among them, tk-tk- 1 =tk- 1 -tk- 2 =... =t 2 -t 1 =p, i.e., increasing time delay subsequence TZ k ={t 1 ,t 2 ,...t k-1 ,t k}Use the linear distribution strategy, the interval length is p, and the maximum interval length satisfies:

[0013] Furthermore, for the increasing time delay subsequence TZM k ={t k+1 ,t k+2 ,...,t M-1 ,t M}, adopt linear distribution, exponential distribution or other distribution strategies.

[0014] Step 3: According to the delay sequence T M Collect transient absorption spectrum data under different time delays to form a transient absorption spectrum data matrix with M rows and N columns:

[0015]

[0016] where a ij represents the transient absorption data of the jth wavelength value at the i-th time delay;

[0017] At the same time, obtain the wavelength vector composed of N wavelength values:

[0018]

[0019] Step 4: Generate a corrected transient absorption spectrum data matrix A′, including:

[0020] Determine the dispersion correction function f(w) according to the optical path characteristics and sample characteristics of the transient absorption spectrometer, where w is the wavelength value;

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

[0022]

[0023] Take out each column vector of matrix A in step 3 To represent the kinetic data at the qth wavelength, perform the following operations:

[0024] Using the dispersion correction function of formula (3), according to the increasing time delay sequence T M Generate a new interval partition sequence:

[0025] S M ={t 1 -f(w q ),t 2 -f(w q ),...,t M-1 -f(w q ),t M -f(w q )}, where w q is the qth wavelength value;

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

[0027] Case 1: Correction interpolation function g q (t) is the linear interpolation model, which must satisfy:

[0028]

[0029] Case 2: Correction interpolation function g q (t) is the nonlinear interpolation model, which must satisfy:

[0030]

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

[0032]

[0033] According to the correction interpolation function g q (t) Generate a column vector of corrected kinetic data at the qth wavelength

[0034] Generate corrected transient absorption spectroscopy data matrix

[0035] Step 5: The column vector of the corrected kinetic data at the qth wavelength obtained in step 4 By performing intrinsic spectrum dynamics fitting, an accurate transient absorption spectrum dynamics equation is obtained, thereby realizing the fitting of transient absorption spectrum dynamics.

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

[0037]

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

[0039]

[0040] Among them, d 0 is a constant, U represents the number of components, t 0 Used to correct the time zero point, τ i is the characteristic time constant of the i-th exponential decay component, B i is the characteristic intensity constant of the i-th exponential decay component;

[0041] The column vector of the corrected kinetic data at the qth wavelength is selected, and the kinetic fitting function is used for numerical fitting to obtain the relevant parameters of the intrinsic excited state decay kinetic function D(t), decouple the convolution of the pump light, the probe light and the intrinsic spectral dynamics, and fit to obtain the characteristic constants of the intrinsic excited state decay dynamics, thereby obtaining accurate transient absorption spectral dynamics, that is, realizing the fitting of transient absorption spectral dynamics.

[0042] The transient absorption spectrum dynamics device disclosed in the present invention is used to realize the transient absorption spectrum dynamics fitting method. The transient absorption spectrum dynamics device comprises a spectrum acquisition module, a dispersion correction module, a dynamics fitting module and a host computer.

[0043] The spectrum acquisition module is used to acquire transient absorption spectrum data under a preset increasing time delay sequence to obtain a transient absorption spectrum data matrix.

[0044] The dispersion correction module is used to generate the corrected transient absorption spectrum data matrix.

[0045] The kinetic fitting module is used to obtain characteristic constants of intrinsic excited state decay kinetics by fitting the corrected transient absorption spectrum data matrix with the involved kinetic fitting functions.

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

[0047] Furthermore, the spectrum acquisition module includes a femtosecond laser generated by a femtosecond laser, which is divided into a pump light and a detection light by a first beam splitter; the detection light enters an optical delay line, and then enters a supercontinuum white light generation module to generate a supercontinuum white light, which is collected by a spectrometer after passing through a sample to be tested; the pump light passes through a laser frequency domain shaping module to generate a frequency-adjustable femtosecond laser, which is then irradiated onto the sample to be tested through an optical switch, and the pump light and the detection light spots overlap in space on the sample to be tested; the electrical control module is used to control the working timing of the optical switch and the spectrometer, and communicate with the spectrometer, and transmit the transient absorption spectrum data matrix obtained by digital / analog conversion to the dispersion correction module;

[0048] The dispersion correction module receives the transient absorption spectrum data matrix, performs dispersion correction on it, and then transmits the corrected transient absorption spectrum data matrix to the dynamic fitting module;

[0049] The dynamic 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 a second beam splitter, and the detection 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 detection light, and combine the corrected transient absorption spectrum data matrix to realize the transient absorption spectrum dynamic fitting function.

[0050] Furthermore, the spectrum acquisition module includes a pump light generated by a pump laser irradiating the sample to be tested; the supercontinuum white light emitted by the detection laser is used as the detection light, which is divided into two parts by a first beam splitter, one part is collected by a first spectrometer after passing through the sample to be tested, and the other part is collected by a second spectrometer; the electrical control module receives the synchronous output signal of the pump laser, and triggers the detection laser in an external triggering manner after a certain time delay, thereby generating a preset time delay between the pump light and the detection 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 / analog conversion to the dispersion correction module;

[0051] The dispersion correction module receives the transient absorption spectrum data matrix, performs dispersion correction on it, and then transmits the corrected transient absorption spectrum data matrix to the dynamic fitting module;

[0052] The dynamic 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 a beam splitter, and the probe light enters the second pulse width analysis module through a 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 combine the corrected transient absorption spectrum data matrix to realize the transient absorption spectrum dynamic fitting function.

[0053] Beneficial effects:

[0054] 1. The present invention discloses a fitting method and device for transient absorption spectral dynamics, which describes the convolution of pump light, probe light and intrinsic spectral dynamics through time domain characterization and fitting of pump light and probe light, and obtains accurate intrinsic transient absorption dynamics through fitting model, eliminates the influence of pump light and probe light pulse width on transient absorption spectral dynamics, eliminates system errors, and thus obtains accurate intrinsic transient absorption spectral dynamics, which is of great significance for the characterization of photophysical and photochemical properties of optoelectronic materials with short carrier relaxation time.

[0055] 2. The present invention discloses a fitting method and device for transient absorption spectrum dynamics, which eliminates the influence of pump light and probe light pulse width on transient absorption spectrum dynamics and system errors by describing the convolution of pump light, probe light and intrinsic spectrum dynamics. It can still decouple the intrinsic transient absorption spectrum dynamics when the carrier relaxation time is shorter than the laser pulse width.

[0056] 3. The present invention discloses a fitting method and device for transient absorption spectrum dynamics. By describing the convolution of pump light, probe light and intrinsic spectrum dynamics, the influence of pump light and probe light pulse width on transient absorption spectrum dynamics is eliminated, and system errors are eliminated. The pulse width requirement for pump laser or probe laser in transient absorption spectrum can be reduced, so that lasers with longer laser pulse width can also be applied to transient absorption spectrum, so that the equipment maintains a high time resolution and reduces the overall cost of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0058] Figure 1 The present invention provides a flowchart of a method for kinetic fitting of transient absorption spectra according to an embodiment of the present invention.

[0059] Figure 2 It is a schematic diagram of the principle of the first transient absorption spectrum dynamic fitting provided according to an embodiment of the present invention.

[0060] Figure 3 It is a schematic diagram of the principle of the second transient absorption spectrum dynamic fitting provided according to an embodiment of the present invention.

[0061] Figure 2 The various parts in the system 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 tested; 6—optical switch; 7—spectrometer; 8—electrical control module; 9—dispersion correction module; 10—dynamic 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 various parts are explained as follows: 16—pump laser; 17—detection laser; 18—sample to be tested; 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—dynamic fitting module; 31—host computer. DETAILED DESCRIPTION

[0063] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0064] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0065] Embodiment 1:

[0066] Figure 2 This is a schematic diagram of the principle of the first transient absorption spectrum dynamic fitting according to an embodiment of the present invention. This solution is generally used when the time resolution of the transient absorption spectrum is required to be in the femtosecond level and the detection time window is in the nanosecond level. Figure 2 As shown, the femtosecond laser generated by the femtosecond laser 1 is divided into pump light and detection light by the beam splitter 13; after the detection light is split by the beam splitter 14, a part of the detection light enters the second pulse width analysis module 12, and the other part of the detection light 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 to be tested 5; the pump light passes through the laser frequency domain shaping module 2 to generate frequency-adjustable femtosecond laser, and then passes through the optical switch 6. After the pump light passes through the beam splitter 15, a part of the pump light enters the first pulse width analysis module 11, and the other part of the pump light is irradiated on the sample 5, and the light spots of the pump light and the detection light are Overlap on the sample; the electrical control module 8 is used to control the working timing of the optical switch 6 and the spectrometer 7, and communicate with the spectrometer 7 to transmit the transient absorption spectrum data matrix obtained by digital / analog conversion to the dispersion correction module 9; the dispersion correction module 9 transmits the corrected transient absorption spectrum data matrix to the dynamic fitting module 10; the host computer 14 communicates with the dynamic 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 time domain characteristics of the pump light and the detection light, and transmit the above-mentioned time domain characteristics to the dynamic fitting module 10, so as to realize the function of transient absorption spectrum dynamic fitting.

[0067] Based on the kinetic fitting method of the transient absorption spectrum of this embodiment, the specific implementation steps are as follows:

[0068] S10. Time domain characterization and fitting of pump light and probe light;

[0069] The time domain characteristics of the pump light and the detection light are characterized and fitted respectively, and the pulse time domain distribution characteristics of the pump light and the pulse time domain distribution characteristics of the detection light are obtained;

[0070] The time domain distribution of the pump light and the probe light is defined as follows:

[0071]

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

[0073]

[0074] The obtained pulse time domain distribution characteristics of the pump light or the pulse time domain distribution characteristics of the detection light are fitted by using equations (9) and (10), and the half-width T of the pump light and the detection light are obtained by normalized fitting. 1 , T 2 ;

[0075] The first pulse width analysis module and the second pulse width analysis module can select a self-correlator to characterize and analyze the time domain characteristics of the pump light and the detection light with a time resolution of the order of femtoseconds.

[0076] S11. Set time delay sequence;

[0077] The time delay sequence of the femtosecond transient absorption spectrum is determined by the host computer. The incrementing time delay sequence T with M elements is preset. M ={t 1 ,t 2 ,t 3 ,...,t k-1 ,t k ,t k+1 ,...,t M}. Among them, tk-tk- 1 =tk- 1 -tk- 2 =... =t 2 -t 1 =p, i.e., increasing time delay subsequence TZ k ={t 1 ,t 2 ,...t k-1 ,t k}Use the linear distribution strategy, the interval length is p, and the maximum interval length meets the following conditions: For example, considering that the laser pulse width emitted by a femtosecond laser is 0.2ps, the interval length p is set to 0.04ps; the increasing time delay subsequence TZ is set to -1ps, -0.96ps, -0.92ps, ..., 0.92ps, 0.96ps, 1ps; the upper computer 14 controls the position of the optical delay line 3 to adjust the optical path difference between the pump light and the detection light.

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

[0079] S12. sequentially collecting transient absorption spectrum data under a preset time delay sequence;

[0080] According to the delay sequence T M Collect transient absorption spectrum data under different time delays to form a transient absorption spectrum data matrix with M rows and N columns:

[0081]

[0082] where a ij represents the transient absorption data of the jth wavelength value at the i-th time delay;

[0083] At the same time, obtain the wavelength vector composed of N wavelength values:

[0084]

[0085] S13. generating a corrected transient absorption spectrum data matrix;

[0086] Determine the dispersion correction function f(w) according to the optical path characteristics and sample characteristics of the transient absorption spectrometer, where w is the wavelength value;

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

[0088]

[0089] Take out each column vector of matrix A in step 3 To represent the kinetic data at the qth wavelength, perform the following operations:

[0090] Using the dispersion correction function of formula (11), according to the increasing time delay sequence T M Generate a new interval partition sequence:

[0091] S M ={t 1 -f(w q ),t 2 -f(w q ),...,t M-1 -f(w q ),t M -f(w q )}, where w q is the qth wavelength value;

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

[0093] Case 1: Correction interpolation function g q (t) is the linear interpolation model, which must satisfy:

[0094]

[0095] Case 2: Correction interpolation function g q (t) is the nonlinear interpolation model, which must satisfy:

[0096]

[0097] Among them, L j (t) is called the basic nonlinear interpolation function and must satisfy:

[0098]

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

[0100]

[0101] Generate corrected transient absorption spectroscopy data matrix

[0102] S14. Dynamic fitting of intrinsic spectra;

[0103] The column vector of the corrected kinetic data at the qth wavelength obtained in step 4 The intrinsic spectral dynamics fitting is performed to obtain accurate transient absorption spectral dynamics.

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

[0105]

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

[0107]

[0108] Among them, d 0 is a constant, U represents the number of components, t 0 Used to correct the time zero point, τ i is the characteristic time constant of the i-th exponential decay component, B i is the characteristic intensity constant of the i-th exponential decay component;

[0109] The column vector of the corrected kinetic data at the qth wavelength is selected and numerically fitted using the kinetic fitting function to obtain the relevant parameters of the intrinsic excited state decay kinetic function D(t). The convolution of the pump light, probe light and intrinsic spectral dynamics is decoupled and fitted to obtain the characteristic constants of the intrinsic excited state decay dynamics, thereby obtaining accurate transient absorption spectral dynamics.

[0110] Embodiment 2:

[0111] Figure 3 This is a schematic diagram of the principle of the second transient absorption spectrum dynamic fitting according to an embodiment of the present invention. This solution is generally used when the time resolution of the transient absorption spectrum is required to be in the sub-nanosecond to nanosecond level and the detection time window is in the microsecond to millisecond level. Figure 3As shown, the pump light generated by the pump laser 16 is irradiated on the sample to be tested 18; the supercontinuum white light emitted by the detection laser 17 is used as the detection light, which is divided into two parts by the first beam splitter 22, one part is collected by the first spectrometer 19 after passing through the sample to be tested 18, and the other part is collected by the second spectrometer 20; the electrical control module 27 receives the synchronous output signal of the pump laser 16, and triggers the detection laser 17 in an external triggering manner after a certain time delay, thereby generating a preset time delay of the pump light and the detection light; the time domain characteristics of the pump light and the detection light are respectively determined by the first pulse width analysis module 27 and the second pulse width analysis module 27. The module 24 is characterized by the second pulse width analysis module 25, and sent to the time interval analysis module 16 for analyzing the actual time delay of the pump light and the detection light; the above data is 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, and sends the obtained transient absorption spectrum matrix to the dispersion correction module 29; the dispersion correction module 29 transmits the corrected transient absorption spectrum data matrix to the dynamic fitting module 30 to realize the dynamic fitting function; the host computer 31 communicates with the dynamic fitting module 30 and realizes the interaction with the user.

[0112] Based on the kinetic fitting method of the transient absorption spectrum of this embodiment, the specific implementation steps are 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 detection light are characterized and fitted respectively, and the pulse time domain distribution characteristics of the pump light and the pulse time domain distribution characteristics of the detection light are obtained;

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

[0116]

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

[0118]

[0119] The obtained pulse time domain distribution characteristics of the pump light or the pulse time domain distribution characteristics of the detection light are fitted by using equations (17) and (18), and the half-width T of the pump light and the detection light are obtained by normalized fitting. 1 、T 2 ;

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

[0121] S11. Set time delay sequence;

[0122] The time delay sequence of the nanosecond transient absorption spectrum is determined by the host computer. The incrementing time delay sequence T with M elements is preset. M ={t 1 ,t 2 ,t 3 ,...,t k-1 ,t k ,t k+1 ,...,t M}. Among them, tk-tk- 1 =tk- 1 -tk- 2 =... =t 2 -t 1 =p, i.e., increasing time delay subsequence TZ k ={t 1 ,t 2 ,...t k-1 ,t k}Use the linear distribution strategy, the interval length is p, and the maximum interval length meets the following conditions: 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, let the interval length p be 0.2ns; set the incremental time delay subsequence TZ 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}, adopt linear distribution or exponential distribution or other distribution strategies to achieve. For example, adopt the linear distribution strategy, the increasing time delay subsequence TZM k 4ns, 6ns, 8ns…, 96ns, 98ns, 100ns.

[0124] S12. sequentially collecting transient absorption spectrum data under a preset time delay sequence;

[0125] According to the delay sequence T M Collect transient absorption spectrum data under different time delays to form a transient absorption spectrum data matrix with M rows and N columns:

[0126]

[0127] where a ij represents the transient absorption data of the jth wavelength value at the i-th time delay;

[0128] At the same time, obtain the wavelength vector composed of N wavelength values:

[0129]

[0130] S13. generating a corrected transient absorption spectrum data matrix;

[0131] Determine the dispersion correction function f(w) according to the optical path characteristics and sample characteristics of the transient absorption spectrometer, where w is the wavelength value;

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

[0133]

[0134] Take out each column vector of matrix A in step 3 To represent the kinetic data at the qth wavelength, perform the following operations:

[0135] Using the dispersion correction function of formula (19), according to the increasing time delay sequence T M Generate a new interval partition sequence:

[0136] S M ={t 1 -f(w q ),t 2 -f(w q ),...,t M-1 -f(w q ),t M -f(w q )}, where w q is the qth wavelength value;

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

[0138] Case 1: Correction interpolation function g q (t) is the linear interpolation model, which must satisfy:

[0139]

[0140] Case 2: Correction interpolation function g q (t) is the nonlinear interpolation model, which must satisfy:

[0141]

[0142] Among them, L j (t) is called the basic nonlinear interpolation function and must satisfy:

[0143]

[0144] Generate a column vector of corrected kinetic data at the qth wavelength based on the correction interpolation function gq(t)

[0145]

[0146] Generate corrected transient absorption spectroscopy data matrix

[0147] S14. Dynamic fitting of intrinsic spectra;

[0148] The column vector of the corrected kinetic data at the qth wavelength obtained in step 4 The intrinsic spectral dynamics fitting is performed to obtain accurate transient absorption spectral dynamics.

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

[0150]

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

[0152]

[0153] Among them, d 0 is a constant, U represents the number of components, t 0 Used to correct the time zero point, τ i is the characteristic time constant of the i-th exponential decay component, B i is the characteristic intensity constant of the i-th exponential decay component;

[0154] The column vector of the corrected kinetic data at the qth wavelength is selected and numerically fitted using the kinetic fitting function to obtain the relevant parameters of the intrinsic excited state decay kinetic function D(t). The convolution of the pump light, probe light and intrinsic spectral dynamics is decoupled and fitted to obtain the characteristic constants of the intrinsic excited state decay dynamics, thereby obtaining accurate transient absorption spectral dynamics.

[0155] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for fitting transient absorption spectral dynamics, characterized in that: The following steps are included: Step 1: characterize and fit the time domain characteristics of the pump light and the detection light respectively to obtain the pulse time domain distribution characteristics of the pump light and the pulse time domain distribution characteristics of the detection light; The time domain distribution of the pump light and the probe light is defined as follows: Where i = 1 represents the pump light, i = 2 represents the probe light; t represents time, T i Used to characterize the full width at half maximum of pulsed laser; C i is a constant, obtained by formula (2): The obtained pulse time domain distribution characteristics of the pump light or the pulse time domain distribution characteristics of the detection light are fitted by using equations (1) and (2), and the half-widths T1 and T2 of the pump light and the detection light are obtained by normalized fitting; Step 2: The time delay sequence with M increasing elements is T M ={t1,t2,t3,...,t k-1 ,t k ,t k+1 ,...,t M }; where tk-tk-1=tk-1-tk-2=...=t2-t1=p, i.e., the increasing time delay subsequence TZ k ={t1,t2,...t k-1 ,t k }Use the linear distribution strategy, the interval length is p, and the maximum interval length satisfies: Step 3: According to the delay sequence T M Collect transient absorption spectrum data under different time delays to form a transient absorption spectrum data matrix with M rows and N columns: where a ij represents the transient absorption data of the jth wavelength value at the i-th time delay; At the same time, obtain the wavelength vector composed of N wavelength values: Step 4: Generate a corrected transient absorption spectrum data matrix A′, including: Determine the dispersion correction function f(w) according to the optical path characteristics and sample characteristics of the transient absorption spectrometer, where w is the wavelength value; The dispersion correction function takes the form of an R-order polynomial function, where n represents the polynomial term of degree n, and c n Represents the fitting constant of the sub-term of order n: Take out each column vector of matrix A in step 3 To represent the kinetic data at the qth wavelength, perform the following operations: Using the dispersion correction function of formula (3), according to the increasing time delay sequence T M Generate a new interval partition sequence: S M ={t1-f(wq),t2-f(wq),...,t M-1 -f(wq),t M -f(wq)}, where w q is the qth wavelength value; According to S M The correction interpolation function g at the qth wavelength is q (t), represents the wavelength w q Dispersion-corrected transient absorption kinetics data at time t: Case 1: Correction interpolation function g q (t) is the linear interpolation model, satisfying: Case 2: Correction interpolation function g q (t) is the model of nonlinear interpolation, satisfying: Among them, L j (t) is called the basic nonlinear interpolation function and must satisfy: According to the correction interpolation function g q (t) Generate a column vector of corrected kinetic data at the qth wavelength Generate corrected transient absorption spectroscopy data matrix Step 5: The column vector of the corrected kinetic data at the qth wavelength obtained in step 4 Perform intrinsic spectrum dynamics fitting to obtain accurate transient absorption spectrum dynamics equation and realize transient absorption spectrum dynamics fitting; The following kinetic fitting function was used for kinetic fitting: Where ΔA(t) represents the transient absorption kinetic data at time t, and D(t) represents the intrinsic excited state decay kinetic function of the sample to be tested, which is expressed as: Among them, 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 exponential decay component, B i is the characteristic intensity constant of the i-th exponential decay component; The column vector of the corrected kinetic data at the qth wavelength is selected, and the kinetic fitting function is used for numerical fitting to obtain the relevant parameters of the intrinsic excited state decay kinetic function D(t), decouple the convolution of the pump light, the probe light and the intrinsic spectral dynamics, and fit to obtain the characteristic constants of the intrinsic excited state decay dynamics, thereby obtaining accurate transient absorption spectral dynamics, that is, realizing the fitting of transient absorption spectral dynamics.

2. The method for fitting transient absorption spectrum dynamics according to claim 1, characterized in that: In step 2, for the increasing time delay subsequence TZM k ={t k+1 ,t k+2 ,...,t M-1 ,t M }, adopt linear distribution, exponential distribution or other distribution strategies to achieve it.

3. A transient absorption spectrum dynamics fitting device, used to implement the method as claimed in claim 1 or 2, characterized in that: It includes spectrum acquisition module, dispersion correction module, dynamic fitting module and host computer; The spectrum acquisition module is used to acquire 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 to generate a corrected transient absorption spectrum data matrix; The kinetic fitting module is used to obtain characteristic constants of intrinsic excited state decay kinetics by fitting the corrected transient absorption spectrum data matrix with the involved kinetic fitting function; The host computer is used to control the work of the spectrum acquisition module, dispersion correction module and dynamic fitting module, display the test results, and realize human-computer interaction function.

4. The device according to claim 3, characterized in that: The spectrum acquisition module includes a femtosecond laser generated by a femtosecond laser, which is divided into a pump light and a detection light by a first beam splitter; the detection light enters an optical delay line, and then enters a supercontinuum white light generation module to generate a supercontinuum white light, which is collected by a spectrometer after passing through a sample to be tested; the pump light passes through a laser frequency domain shaping module to generate a frequency-adjustable femtosecond laser, which is then irradiated on the sample to be tested through an optical switch, and the pump light and the detection light spots overlap in space on the sample to be tested; the electrical control module is used to control the working sequence of the optical switch and the spectrometer, and communicate with the spectrometer, and transmit the transient absorption spectrum data matrix obtained by digital / analog conversion to the dispersion correction module; The dispersion correction module receives the transient absorption spectrum data matrix, performs dispersion correction on it, and then transmits the corrected transient absorption spectrum data matrix to the dynamic fitting module; The dynamic 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 a second beam splitter, and the detection 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 detection light, and combine the corrected transient absorption spectrum data matrix to realize the transient absorption spectrum dynamic fitting function.

5. The device according to claim 3, characterized in that: The spectrum acquisition module includes a pump light generated by a pump laser irradiating the sample to be tested; a supercontinuum white light emitted by a detection laser is used as detection light and is divided into two parts by a first beam splitter, one part is collected by a first spectrometer after passing through the sample to be tested, and the other part is collected by a second spectrometer; an electrical control module receives a synchronous output signal of the pump laser, and triggers the detection laser in an external triggering manner after a certain time delay, thereby generating a preset time delay between the pump light and the detection light; a data communication module communicates with the first spectrometer and the second spectrometer, and transmits the transient absorption spectrum data matrix obtained by digital / analog conversion to a dispersion correction module; The dispersion correction module receives the transient absorption spectrum data matrix, performs dispersion correction on it, and then transmits the corrected transient absorption spectrum data matrix to the dynamic fitting module; The dynamic 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 a beam splitter, and the probe light enters the second pulse width analysis module through a 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 combine the corrected transient absorption spectrum data matrix to realize the transient absorption spectrum dynamic fitting function.

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