为了消除在激光诱导击穿光谱(LIBS)信号检测时等离子体中强的轫致电子辐射对光电倍增管和前置信号放大器造成的不良影响, 提高信号检测灵敏度, 设计了一种基于CR110的门控端窗光电倍增管并用于LIBS中的微弱信号检测。该门控光电倍增管与前置信号放大器组合运用既可以成功抑制激光等离子体中强的轫致电子辐射的背景干扰, 又可以进一步放大微弱的原子辐射信号, 提高光谱分析的灵敏度。用LIBS分析铝合金标样中的微量铬元素, 采用该门控光电倍增管时其检出限可以达到5.55 ppm, 与采用普通光电倍增管的相比改善了近6倍, 显示出该门控光电倍增管在时间分辨信号检测领域良好的应用效果。

In order to eliminate the influence of strong Bremsstrahlung emission existed in laser-induced plasma on photomultiplier tube (PMT) and preamplifier and to improve signal detection sensitivity of laser-induced breakdown spectroscopy (LIBS), an end-on gated PMT was designed based on CR110 PMT and was used in weak signal detection of LIBS. The influence of strong Bremsstrahlung emission of the plasma could be successfully eliminated and the weak atomic emission signal could be further amplified after using this gated PMT combined with a preamplifier in signal detection, thus the spectral analysis sensitivity could be improved significantly. In analysis of chromium in aluminum alloy samples by LIBS, the limit of detection of chromium reached 5.55 ppm using this gated PMT as the signal detector, the detectability was improved nearly 6 folds in comparison with that using normal PMT. It was demonstrated that application of this gated photomultiplier tube in time-resolved signal detections could give good measurement results.