一种用于荧光皮秒时间分辨光谱的测试系统

本文详细描述了一种由氩离子锁模激光器、样品池、分光系统及微微秒条纹相机构成的用于测试低强度荧光微微秒时间分辨光谱的系统。给出了典型样品的测试结果:时间分辨率为10ps,光谱范围为500Å—800Å。最后对测量结果进行了分析讨论。

A SYSTEM FOR MEASURING PICOSECOND FLUORESCENCE TIME-RESOLVED SPECTRA

In this paper, a new system for measuring picosecond time-resolved spectra of low-light-level fluorescence is described in detail. The system consists of a pulse light source, a fluorescence emission system, a light splitting system and a streak camera system. The light pulse source is an active mode locked Ar⁺ laser with repeatation rate of 82 MHz and pulse width of approximately 200 ps. The average power of the mode locked Ar⁺ laser is about 800 mw. The fluorescence emission system is made of two lenses and a specially made sample cell. The light splitting svstrem is a grating-type double monochromator with spectral resolution of 0.2 A. A non-synchronous scaning streak camera with time resoletion of 2 ps is used as a time dispersion unit, which ineludr a SIT TV camera and a computer-based data processing system. To insure the synchronization between the laser and the streak camera, a special interface is made.For typical fluorescent samples such as Rhodemine-6G and Acrid ine-Red, the dependences of fluorescence live time with solution concentration, type of solvents, fluorescence wavelength and polarization of laser pulse are carefully measured and measurement results with time resolution of 10 ps are obtained. The experimental results have shown that the new system is an effective mean for measuring fluorescence live time ranging from subn.annsecond to 10 ns.For improving signal-to-noise ratio of the measurements, much atrention has to be taken to the design of the sample cell and the selection of the fluorescence collecting lens. In addition, it is very important for the whole system to be adjusted carefully.Factors affecting the accuracy of the measurements such as the width of the laser pulse, the time resolution of the streak camera, the rime dispersion of the monochromator and the drive jitter of the streak camera etc. are discussed.