JPH0392750A - Time-resolution spectrometric apparatus - Google Patents

Abstract

PURPOSE:To make it possible to measure a sample whose reaction period is fast by generating a stimulus which is asynchronous with a reference signal in an interferometer, delaying the stimulus by a delay time for measurement, and sampling the outputs of a detector. CONSTITUTION:Light emitted from a light source 1 is projected on a sample 3 through a rapid-scan interferometer 2. The sample 3 is an object to be mea sured whose reaction indicates the same response to stimulus repeatedly. A stimulus generator 4 generates a trigger (a) having a constant period t' which asynchronous with a reference signal in the interferometer 2. The trigger is imparted to the sample 3 and supplied to a variable type delay circuit 5 as a synchronizing singal (b). The circuit 5 generates a trigger (c) which is delayed by DELTAgamma' and controls a gate circuit 8. The output signal from the gate circuit 8 is detected with a detector 6. The detected signal is made to pass the gate circuit 8 through a preamplifier 7. Only the signal having the constant delay time is sampled, and comb-shaped interferogram is obtained. The signal is inputted into a CPU 12 through a low-pass filter LPF 9, a main amplifier 10 and an AD converter 11.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention periodically generates a stimulus using a stimulus generating means, repeatedly applies it to a measurement object, and samples the output of a detector using a rapid scan interferometer. The present invention relates to a time-resolved spectroscopic measuring device that measures the reaction state of a measurement object that repeatedly shows the same response to a stimulus by obtaining an interfaelogram for a certain delay time from a stimulus and obtaining a spectrum by Fourier transformation.

[Conventional technology]

The need to periodically apply stimulation to a sample using electricity, laser, or other means and measure the reaction state during the process of recovery from the stimulation is needed, for example, when evaluating the characteristics of liquid crystals, and in various other fields. be. As a measurement method, there is a time-resolved spectroscopy using FT-IR (Fourier transform infrared spectrophotometer). This method has been developed and used in the past because it can measure a wide wavenumber range with a high signal-to-noise ratio, and can be classified into those using a rapid scan interferometer and those using a step scan interferometer.

FT-IR uses an interferometer consisting of a semi-transparent mirror, a movable mirror, and a fixed mirror, and moves the movable mirror to obtain an ink ferrodrum, whereas an ink ferogram measures characteristics such as transmittance of a sample. There is a condition that the sample must be constant, and if the characteristics of the sample change, when it is Fourier transformed, information different from the original information will be obtained.

Therefore, in time-resolved spectroscopy, the period of stimulation applied must be longer than the time required for the reaction to end; however, when applying periodic stimulation, it is difficult to It will be necessary to achieve consistency. Therefore, conventionally, stimulation is applied in synchronization with a reference signal possessed by an interferometer.

FIG. 4 is a diagram for explaining a conventional example of time-resolved spectroscopy.

In the case of using a labid scan interferometer, as mentioned above, the stimulation is synchronized with the reference signal of the interferometer and the ink ferrodrum is collected. Can be divided.

■ If the response to the stimulus is very slow, that is, the period τ of the object's response or similar state change is longer than the scanning time T of the moving mirror (the time for one measurement of the entire interferodrum obtained by the interferometer) (τ > T) ■ If the response to the stimulus is relatively slow, that is, the time interval (sampling interval) for measuring each point of the point cloud forming the ink ferrodalum is longer than t (1 < τ < T) ■ The stimulus In the case where the response to If the scanning speed is increased, the interferodalum will be removed at a certain delay in the applied stimulus, so
By Fourier transforming this, a spectrum of a certain target state can be obtained.

However, in the case of ■, the reaction time is shorter, so
As shown in Figure 4(b), multiple scans are performed to
Second interferometer scan, second interferometer scan,
The spectrum of a certain state can be calculated by shifting the stimulus timing by the interval t of the reference signal of the interferometer, and by identifying and editing data with the same delay time and creating an ink ferrogram. will be taken out.

In the case of ■, the reaction period τ is included in the sampling period t, so as shown in Figure 4 (C), repeated stimulation is applied in synchronization with the reference signal of the interferometer, and a constant delay is applied. A spectrum in a certain state is extracted by measuring at a time Δτ and editing data with the same delay time to create an interferodrum.

[Problems to be Solved by the Invention] However, especially in the case of (2) above, it is necessary to synchronize with the reference signal of the interferometer and to perform very fast measurement. For example, if the sampling period t is 100 μs, 10
If you try to measure the 0 point, you will have to repeat the measurement every 1 μs, and one scan of the moving mirror will result in non-'j:
9 will have to import and process data on human capacity. Moreover, after measurement, each data must be identified and data with the same delay time must be edited. Then, F
As for the TrR, it is necessary to add <= h functions that have not been provided in the past, such as a high-speed sampling mechanism and a data editing function.

Furthermore, if the reaction period is shorter than the sampling time, there will be dead time until the next sampling after the reaction is completed, and measurement efficiency will deteriorate.

Furthermore, in the case of the above example, the stimulation is applied in synchronization with the reference signal of the interferometer, but it is difficult to achieve such synchronization, and it is difficult to achieve such synchronization when the stimulation is naturally periodic. However, there is a problem in that it cannot be measured using the method described in 2.

The present invention solves the above-mentioned problems, and aims to provide a time-resolved spectrometer that can measure a sample with a fast reaction period asynchronously with a reference signal of an interferometer. .

[Means to solve the problem]

To this end, the present invention periodically generates a stimulus using a stimulus generating means and repeatedly applies it to the measurement target, samples the output of a detector using a rapid scan interferometer, and obtains an interferodynamic value for a certain delay time from the stimulus. , a time-resolved spectroscopic measurement device that measures the reaction state of a measurement target that repeatedly shows the same response to a stimulus by obtaining a spectrum by Fourier transformation, the gate circuit gating the detector output, and connected to the gate means. It is equipped with a delay means that controls a gate circuit by delaying a predetermined time in synchronization with the stimulus, and generates the stimulus asynchronously with the reference signal of the interferometer. This device is characterized in that it is configured to sample the output.

[Effect]

The time-resolved spectrometer of the present invention includes a gate circuit for gating the detector output, a low-pass filter connected to the gate means, and a delay means for controlling the gate circuit by delaying the gate circuit by a predetermined period of time in synchronization with the stimulus. The stimulus is generated asynchronously with the reference signal of the meter, and the detector output is sampled with a delay of the desired delay time, so it is possible to obtain the interferometry for a certain delay time and obtain the spectrum by Fourier transformation. Furthermore, by successively changing the delay time and making similar measurements, a series of time-series spectra for different delay times can be obtained.

Moreover, since there are no restrictions on the stimulus generator, it is possible to measure fast reactions by raising the frequency of <ilil1, which is unrelated to the reference signal of the interferometer. Further, even in a conventional device using a rapid scan interferometer, it can be realized by adding simple means without making any major changes to the system.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the time-resolved spectrometer according to the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the time-resolved spectrometer according to the present invention.

In Figure 1, 1 is a light source, 2 is an interferometer, 3 is a sample, and 4
is a stimulus generator, 5 is a variable delay circuit, 6 is a detector, 7 is a preamplifier, 8 is a gate circuit, 9 is a low-pass filter,
10 is the main amplifier, 11 is the ΔD converter, 12 is the CPU
shows. The stimulus generator 4 includes an interferometer 2 as shown in FIG.
Stimulation (
The variable delay circuit 5 generates a trigger delayed by a fixed time Δτ' from the synchronization signal of the stimulus generator 4 to control the gate circuit 8. The gate circuit 8 has a period t' like the 80 converter.
By passing the signal only between the two gates, a comb-shaped signal is obtained, as shown in FIG. 3(d). In other words, a comb-like interferogram is obtained by gating repeated signals with a certain delay time from the stimulus and sampling only signals with a certain delay time from the stimulus. The low-pass filter 9 is used to remove harmonics obtained from the output of the gate circuit 8 to obtain an envelope of the output of the gate circuit 8.

As a result, the comb-like interferodalum is converted into a normal analog signal.

The sample 3 used in the system of the present invention is a measurement object that repeatedly shows the same response to a stimulus, and the reaction period τ of the object is shorter than the sampling interval t of each point of the interfaerodrum.

According to the above structure, the output of the detector 6 when the sample 3 does not change is <σ; wave number - 1/λ) (1), but when a stimulus is applied to the sample 3 The output of the detector 6 when gated with a constant delay △τ′ zumbling at equal intervals, so the comb function [1
1. ( 1 + cos2 yr a x
) dσ−(2). Here, if the speed of the movable mirror of the interferometer is V, then X=2νt, but there is no phase relationship because the periodic stimulation is asynchronous with the movement of the movable mirror. In (1+cos2πσX) of equation (2) above, only the term multiplied by cos2πσX can be converted into a spectrum, so if only this term is extracted, the output is F ''(X) = River, · (t - △τ Then, in order to see the output obtained when this signal is passed through the low-pass filter 9, 11J,·(t-△τ") is Fourier transformed with t, = e-"""(1/t')147t'(f) --
----(3) = 1/t' Cδ(f) +δ(f-1/
t') e-" and +-...-+δ(f+i/t')e
``'?+.'', which is also a comb function.Moreover, it appears at an interval that is the reciprocal of the sampling interval.Therefore,
Passing through the low-pass filter 9, 11.(4) is obtained as the output. Comparing this equation (4) with the above equation (1), the equation of F''(X) becomes il
It is shown that the ink ferrodurum in the state of the sample was obtained after a delay of △τ' after applying illumination. Therefore, AD conversion may be performed at a sampling interval determined by the wave number band of the signal.

Note that the present invention is not limited to the above embodiments, and various modifications are possible. For example, the function of the gate circuit itself may be performed by an AD converter. In this case, since the phase differs for each scan of the movable mirror, the phase correction is performed on the no-ink fluorodulum for each scan by FT to form a spectrum, which is then integrated. Further, the gate circuit may be replaced by turning on/off the voltage supplied to the detector in synchronization with the trigger signal from the stimulation generator. Furthermore, FT Raman (τ′=O
) and FT photoluminescence. In this case, the pulse laser 26 is directly applied to the sample 21 as shown in FIG.
The light from is captured by the detector 23 through the interferometer 22,
The same processing as in the embodiment shown in FIG. 1 is performed. In the former case, since τ'-0 is used, the gate circuit 25 and delay circuit 27 may be omitted and a low-pass filter may be connected directly to the preamplifier 24, or the delay circuit may be A circuit 27 may also be set.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the stimulation can be applied asynchronously with the reference signal of the interferometer, so that restrictions on stimulation can be significantly relaxed. Furthermore, since the stimulation frequency can be increased for fast reactions, measurement efficiency can be improved. Furthermore, by adding a stimulus generator, a variable delay circuit, a gate circuit, and a low-pass filter to a commonly used rapid-scan interferometer device, we can significantly change the system, including the data sampling circuit and data editing software. It can be carried out without the need for

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of one embodiment of the time-resolved spectrometer according to the present invention, FIG. 2 is a waveform diagram for explaining the operation of the time-resolved spectrometer according to the present invention, and FIG. FIG. 4, which is a diagram showing another embodiment of the present invention, is a diagram for explaining a conventional example of a time-resolved spectrometer. l...Light source, 2...Interferometer, 3...Sample, 4...
・ffilJ Geki Generator, 5... Variable delay circuit, 6.
...Detector, 7...Brieamp, 8...Gate circuit, 9...Low pass filter, 10...Main amplifier, 11...AD converter, l2...CPU0 Applicant: JEOL Co., Ltd.

Claims (2)

[Claims] (1) Periodically generate a stimulus using a stimulus generator and repeatedly apply it to the measurement target, sample the detector output using a rapid scan interferometer to obtain an interferogram for a certain delay time from the stimulus, and use Fourier transform to obtain an interferogram. A time-resolved spectrometer that measures the reaction state of a measurement target that repeatedly shows the same response to a stimulus by obtaining a spectrum, the device comprising: a gate circuit that gates the detector output; and a low-pass filter connected to the gate means. , and a delay means for controlling a gate circuit by delaying a predetermined time in synchronization with the stimulus, so that the stimulus is generated asynchronously with the reference signal of the interferometer, and the detector output is sampled with a delay of the desired delay time. A time-resolved spectroscopic measurement device characterized by the following configuration. (2) The time-resolved spectrometer according to claim 1, characterized in that a pulsed laser is applied to the measurement object as a stimulus.