采用SiPM探测三硝基甲苯的时间分辨拉曼光谱

Time-resolved Raman spectroscopy of trinitrotoluene detected by Silicon Photomultiplier

硅光电倍增器(SiPM)是近年来迅速发展起来的新型固态弱光探测器,有望取代传统的光电倍增器(PMT)用于拉曼检测中。为了解决拉曼检测中的荧光干扰以及Si PM的高暗计数率的缺陷,建立了基于SiPM为光探测器的时间分辨拉曼光谱测量系统。以三硝基甲苯(TNT)为样品,重点研究了其拉曼峰的峰本比(PBR)随选通时间的变化规律。结果表明:随着选通时间增大,拉曼峰的PBR呈现先增大后减小的趋势,最后变化缓慢。当选通时间为400 ps时,该方法所测得拉曼峰的PBR要优于商业拉曼谱仪和参考文献[12]采用的门控方法的结果,并且此时系统所记录的Si PM暗计数水平与PMT相当。该方法在很大程度上实现了对样品荧光和Si PM高暗计数率的抑制,显著提高了拉曼谱的PBR。

Silicon Photomultiplier(SiPM)is a new type of solid state photodetector developed rapidly in recent decades,and has the potential to replace photo multiplier tube(PMT)in the Raman detection.A time-resolved Raman spectroscopy system based on a Silicon Photomultiplier(SiPM)was established in order to limit the influence of intense fluorescence on Raman spectroscopy,and alleviate the high dark count rate(DCR)problem of the SiPM.The variation of the Peak-to-Background Ratio(PBR)of Raman peaks along with counting time was investigated using trinitrotoluene(TNT)as the sample.Results indicate that with counting time increasing,the PBR of Raman peaks is increasing first and then decreasing,finally changing slowly.When counting time is 400 ps,a best PBR is achieved for the Raman peaks.The results are superior to that achieved by the commercial Raman spectrometers and the methods used in the literature.Also,the dark counts system collected are comparable to PMT.The method proposed in the paper is capable of reducing the high fluorescence background and the effects of SiPM′s high DCR to a great extent,facilitating a marked improvement in the Raman PBR.