杂散光及堆积效应对时间分辨光谱的影响

Influence of Scattered Light and Pile-up Effect on Time-resolved Spectroscopy

采用时间相关单光子计数法对YAG:Ce荧光粉的时间分辨光谱进行了测试分析。发现泵浦光源以杂散光的形式进入光谱仪探测器是引起时间分辨光谱失真的重要原因;同时,样品本身发射的大量光子也会引起光子堆积效应,从而使实际测得的时间分辨光谱向短寿命方向偏移。为了获得准确的时间分辨光谱,利用窄带的带通滤光片对泵浦光源的发射带宽进行了校正。结果表明,待测样品仍能被经过滤光片校正的激发光源有效激发;同时,激发光源对样品的时间分辨光谱不再产生干扰作用,充分消除了泵浦光源作为杂散光引起的测试误差。最后通过严格控制检测到的荧光光子数与光源脉冲数的比例,有效降低了光子堆积效应引起的测试误差。

The time-resolved spectra of YAG: Ce phosphors were tested by time-correlated single-photon counting method (TCSPC). It has been found that the light of pump source entering the spectrometer detector in the form of scattered light is an important cause of time-resolved spectral distortion. Simultaneously,a large number of photons emitted by the sample itself can also cause photon pile-up effect. Thereby the actually measured time-resolved spectrum is shifted towards the short life-time direction. In order to obtain an accurate time-resolved spectrum,the emission bandwidth of the pump source is corrected using a narrow-band pass filter. The results show that the filter-corrected pump source is still able to effectively excite the sample and the pump source no longer interferes with the time-resolved spectra of the sample. The test error caused by the excitation light source as scattered light is completely eliminated.Finally,by strictly controlling the ratio of the detected number of fluorescent photons to the number of pulses of the light source,the test error caused by the photon pile-up effect is effectively reduced.