CN108152252A - A kind of integration type femtosecond time resolution fluorescence lifetime measurement spectrometer - Google Patents

Abstract

The present invention relates to time resolution fluorescence spectral measuring instruments, particularly relate to a kind of integration type femtosecond time resolution fluorescence lifetime measurement spectrometer, including detection and pumping laser light path system, fluorescent acquisition system and spectral detection system.This spectrometer excites sample using a branch of femtosecond laser, another beam femtosecond laser causes the sample stimulated radiation of excitation state, all fluorescents being collected into are integrated in spectral detection system, so as to fulfill the measurement of fluorescence lifetime, invention increases the detection sensitivities of fluorescence lifetime measurement.

Description

An integral femtosecond time-resolved fluorescence lifetime measurement spectrometer

technical field

The invention relates to a time-resolved spectrum measuring instrument, specifically an integral femtosecond time-resolved fluorescence lifetime measurement spectrometer. The spectrometer uses a beam of femtosecond laser to excite the sample, and then uses another beam of femtosecond laser to make the sample in the excited state Stimulated radiation reduces the amount of fluorescence emitted by the free radiation of the sample. The spectral detection system integrates all collected sample fluorescence, and compares the integrated fluorescence intensity with and without stimulated radiation to obtain the fluorescence lifetime signal point. The time delay technology realizes the measurement of the femtosecond time-resolved fluorescence lifetime, and the invention increases the detection sensitivity of the fluorescence lifetime measurement.

Background technique

Time-resolved pump-probe technology [Principles and Technical Basis of Ultrafast Laser Spectroscopy, edited by Weng Yuxiang, Chen Hailong, etc., 2013, Chemical Industry Press], also known as excitation-probe double-pulse technology [Basics of Time-Resolved Spectroscopy, Guo Basis, 2012, Higher Education Press], has a wide range of applications in many fields of modern science, such as photophysical processes, photochemical reactions, biochemical processes, photocatalytic reactions, energy and charge transport processes, nanomaterial characterization, etc. Fluorescence lifetime measurement has many applications in the analysis of biological fluorescent probes, solar energy utilization, photophysical and photochemical properties of fluorescent molecules, and research on the dynamics of excited states of substances; . Han Keli et al [Chinese patent application number: 201310392018.6] established a femtosecond time-resolved transient absorption and fluorescence loss two-in-one spectrometer, combining two pump-probe technologies into one spectrometer, extending the femtosecond time-resolved Applications of spectroscopic instruments.

At present, the commonly used fluorescence lifetime measurement instruments mainly include time-correlated single photon counters, streak cameras, femtosecond time-resolved fluorescence up-conversion spectrometers, femtosecond time-resolved fluorescence extinction spectrometers, etc. The time resolution of the time-correlated single photon counter is at the highest tens of picoseconds; the time resolution of the streak camera can reach the picosecond level, but the price is very expensive; the time resolution of the femtosecond time-resolved fluorescence up-conversion spectrometer is limited by the The limitation of the conversion crystal is generally twice the pulse width of the femtosecond laser used; the time resolution of the femtosecond time-resolved fluorescence loss spectroscopy instrument is very high, but it often only measures one fluorescence wavelength when measuring fluorescence, which reduces its Application in fluorescence lifetime measurement of weakly fluorescent substances.

Contents of the invention

The object of the present invention is to obtain an integral femtosecond time-resolved fluorescence lifetime measurement spectrometer, which not only has good time resolution, but also has good fluorescence intensity detection limit.

In order to achieve the above object, the technical scheme adopted in the present invention is:

Integral femtosecond time-resolved fluorescence lifetime measurement spectrometer, including detection and pumping laser optical system, sample fluorescence acquisition system and spectrum detection system;

All components are placed on the optical plate;

The femtosecond laser detection beam and the femtosecond laser pump beam overlap in space on the sample in the sample cell;

The femtosecond laser detection beam and the femtosecond laser pump beam intersect in space, and there is a certain interval in time, and this time interval is adjusted by a time delayer;

The femtosecond laser detection beam is adjusted by the time delayer, passes through the rear reflector of the delayer, and the front reflector of the sample cell, and realizes spatial cross-coincidence with the femtosecond laser pump beam on the sample cell;

The sample fluorescence collection system is that the fluorescence radiated by the sample is collected by the fluorescence collection mirror, reflected by the fluorescence mirror to the fluorescence focusing mirror, focused on the entrance of the optical fiber through the fluorescence focusing mirror, and then introduced into the spectrometer by the optical fiber;

The spectrum measurement system is that after the fluorescence is separated by a spectrometer, a multi-chromatogram is formed on the detector, and the multi-chromatogram on the detector is integrated by a computer to obtain a fluorescence integral signal;

After the optical chopper is running, two fluorescence integral signals without femtosecond laser detection beam and with femtosecond laser detection beam will be obtained on the computer, and the difference between the two fluorescence integral signals is the fluorescence lifetime signal point;

The fluorescence lifetime signal point versus the delay time is plotted as a curve on the computer to obtain the integral femtosecond time-resolved fluorescence lifetime curve of the sample.

The material of the optical plate is duralumin or stainless steel, and its dimensions are: about 120cm in length, about 60cm in width, and about 1cm in thickness;

The fluorescence collecting mirror and the fluorescence focusing mirror can be but not limited to lens, parabolic mirror, spherical mirror;

The sample cell is a cuvette with an optical path of 1mm or 2mm or 10mm;

In the optical chopper, its trigger frequency signal comes from a femtosecond laser, and its chopping frequency is set between 20Hz and 1000Hz;

The detector may be, but not limited to, a photodiode array or a charge-coupled device.

Description of drawings

Fig. 1 is a structural schematic diagram of the integral femtosecond time-resolved fluorescence lifetime measurement spectrometer of the present invention.

Fig. 2 is the integral femtosecond time-resolved fluorescence lifetime measurement curve of the PBBO dye ethanol solution with a concentration of 1 mmol/L in Example 1.

Fig. 3 is the integral femtosecond time-resolved fluorescence lifetime measurement curve of the concentration of 0.1 mmol/L OX750 dye ethanol solution in Example 2. (a) The spectral evolution curve of the fluorescence spectrum of OX750 solution with time; (b) The curve of the fluorescence intensity at 660nm with the delay time (blue solid box) and the total fluorescence intensity after integrating the fluorescence intensity at all wavelengths Curves of latency variation (red empty squares).

Detailed ways

Referring to the accompanying drawings, Fig. 1 is a schematic structural view of the present invention. The optical flat plate described in the integral femtosecond time-resolved fluorescence lifetime measurement spectrometer of the present invention is about 120cm long, and is about 60cm wide, with two light entrances, the first light entrance 2 is the femtosecond laser detection beam entrance, used For the stimulated radiation sample; the second light entrance 3 is the entrance of the femtosecond laser pumping beam, which is used to excite the sample.

All the components are placed on the optical flat plate 1, the femtosecond laser detection beam 2 and the femtosecond laser pumping beam 3 are located in the sample cell 4 and overlap in space, and the femtosecond laser detection beam 2 passes through the time delay device 5. After the adjustment, after passing through the rear reflector 6 of the retarder and the front reflector 7 of the sample cell, the position where the sample in the sample cell 4 is located overlaps with the femtosecond laser pump beam 3 in space;

The femtosecond laser probe beam 2 and the femtosecond laser pump beam 3 are located in the sample cell 4 where the sample is located and overlapped in space and have a specific time interval, and this time interval is adjusted by the time delay device 5;

The sample fluorescence collection system is that the fluorescence radiated by the sample is collected by the fluorescence collection mirror 8, reflected by the fluorescence mirror 9 onto the fluorescence focusing mirror 10, focused on the entrance of the optical fiber 11 through the fluorescence focusing mirror 10, and then introduced into the spectrometer through the optical fiber 12;

The spectrum measurement system is that after the fluorescence is split by the spectrometer 12, a multi-chromatogram is formed on the detector 13, and the multi-chromatogram on the detector 13 is integrated and processed by a computer 14 to obtain a fluorescence integral signal;

After the operation of the optical chopper 15, two fluorescence integral signals without femtosecond laser detection beam and with femtosecond laser detection beam will be obtained on the computer, and the difference between these two fluorescence integral signals is the fluorescence lifetime signal point;

The fluorescence lifetime signal point versus the delay time is drawn into a curve on the computer 14 and fitted to obtain the integral femtosecond time-resolved fluorescence lifetime of the sample.

Fluorescence collecting mirror 8 and fluorescence focusing mirror 10 can be but not limited to lens, parabolic mirror or spherical mirror;

The sample cell 4 is a cuvette with an optical path of 1mm or 2mm or 10mm;

The optical chopper 15, whose trigger frequency signal comes from a femtosecond laser, and whose chopping frequency is set between 20Hz and 1000Hz;

Detector 13 may be, but is not limited to, a photodiode array or a charge-coupled element.

Example 1

Investigate the time resolution capability of the integrated femtosecond time-resolved fluorescence lifetime measuring spectrometer of the present invention in the performance of the integrated femtosecond time-resolved fluorescence lifetime, adopting 1mmol/L of PBBO dye ethanol solution as test sample , to measure integral femtosecond time-resolved fluorescence lifetime signals. The peak of the absorption spectrum of PBBO is around 320nm, only when the two light pulses of the 490nm pump beam and the 800nm probe beam coincide in space and time at the sample in the sample cell, the fluorescence of PBBO will be excited, thus The time-resolved response function of the integral femtosecond time-resolved fluorescence lifetime measurement spectrometer can be obtained. The instrument response function obtained in this embodiment is fitted with a Gaussian function, and the obtained standard deviation is 0.104 picoseconds, and the full width at half maximum is 0.246 picoseconds. See Figure 2 for the experimental data.

Example 2

For the investigation of the fluorescence intensity detection limit performance of the integrated femtosecond time-resolved fluorescence lifetime measurement spectrometer described in the invention, the 0.1mmol/L ethanol solution of OX750 dye is used as the sample; the pump light is 490nm, 1.5mW; the probe light is 800nm , 1mW. The integrated femtosecond time-resolved fluorescence lifetime measurement spectrum of the sample is measured, and the experimental data is shown in Figure 3. Among them, the left figure (a) is the evolution curve of the measured OX750 fluorescence spectrum with the delay time; the right figure (b) includes the decay curve of the fluorescence intensity at a single wavelength of 660nm without integrating the OX750 fluorescence peak with the delay time (blue (red solid box), and the decay curve of integrated fluorescence intensity versus delay time obtained after integrating the OX750 fluorescence peak (red empty box). It can be seen that the noise of the curve after integration is significantly smaller than that before integration. This is a curve showing the generation of OX750 fluorescence signal.

Claims (7)

1. An integral femtosecond time-resolved fluorescence lifetime measurement spectrometer, including a detection and pumping laser optical path system, a sample fluorescence collection system and a spectrum detection system; it is characterized in that: The detection and pumping laser optical path system includes a sample cell, a time delay (5) and an optical chopper (15), and the sample fluorescence collection system includes a spectrometer (12), a detector (13) and a computer (14 ); the femtosecond laser probe beam (2) sent by the femtosecond laser is irradiated to On the sample in the sample cell (4), the femtosecond laser pump beam (3) causes the sample to generate fluorescence; after the sample fluorescence is split by the spectrometer (12), it forms a multi-chromatogram on the detector (13), and the detector (13 ) on the multi-chromatogram is integrated by the computer (14) to obtain the fluorescence integral signal; After the operation of the optical chopper (15), the integrated signal of the wavelength of the fluorescence intensity without the femtosecond laser detection beam and the femtosecond laser detection beam with the femtosecond laser detection beam will be obtained on the computer (14), and the difference between the two fluorescent integrated signals The value is exactly the fluorescence lifetime signal point; take the delay time as the abscissa and the fluorescence lifetime signal point as the ordinate to draw a curve on the computer (14), to obtain the integral femtosecond time-resolved fluorescence lifetime measurement curve of the sample. 2. Integral femtosecond time-resolved fluorescence lifetime measurement spectrometer according to claim 1, is characterized in that: All components in the detection and pumping laser light path system, the sample fluorescence collection system, and the spectrum detection system are placed on the optical flat plate (1). 3. Integral femtosecond time-resolved fluorescence lifetime measurement spectrometer according to claim 1, is characterized in that: In the sample fluorescence collection system, the fluorescence radiated by the sample is collected by the fluorescence collecting mirror (8), reflected by the fluorescence mirror (9) onto the fluorescence focusing mirror (10), and then focused to the optical fiber through the fluorescence focusing mirror (10). (11), then enter the spectrometer (12) from the optical fiber (11); the fluorescence collecting mirror (8) and the fluorescence focusing mirror (10) can be but not limited to lens, parabolic mirror or spherical mirror respectively. 4. integral femtosecond time-resolved fluorescence lifetime measurement spectrometer according to claim 1, is characterized in that: The sample pool (4) is a cuvette with an optical path of 1mm, 2mm or 10mm; the femtosecond laser probe beam (2) and the femtosecond laser pump beam (3) intersect in the space where the sample is located in the sample pool Coincidentally, the femtosecond laser detection beam (2) is regulated by the time delayer (5) and after the optical chopper (15), passes through the rear reflector (6) of the retarder, and the front reflector (7) of the sample cell. The sample cell (4) overlaps with the femtosecond laser pumping beam (3) in space. 5. integral femtosecond time-resolved fluorescence lifetime measurement spectrometer according to claim 1, is characterized in that: Described spectral detection system is that fluorescence forms multi-chromatogram on detector (13) after spectroscopic spectrometer (12) splits light, and multi-chromatogram on detector (13) is integrated by computer (14) to obtain fluorescence integral signal; The device (13) can be, but is not limited to, a photodiode array or a charge-coupled device. 6. Integral femtosecond time-resolved fluorescence lifetime measurement spectrometer according to claim 1, is characterized in that: The trigger frequency of the optical chopper (15) comes from a femtosecond laser, and its chopping frequency is set between 20Hz and 1000Hz. 7. The integral femtosecond time-resolved fluorescence lifetime measurement spectrometer according to claim 1 or 6, characterized in that: The computer (14) is connected to the time delay device (5), the femtosecond laser and the detector (13) through data lines.