利用光热光栅结合近红外荧光研究CC14中Br2激发态的弛豫和猝灭

X. Zhu, J. M. Harris
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引用次数: 0

摘要

利用时间分辨光热光栅结合近红外荧光研究了Br2在CC14中激发态的弛豫和猝灭。由于Br2在CC14中的激发态的非辐射松弛,光热光栅的衍射瞬态信号缓慢上升。近红外荧光测量显示有两种衰变成分;根据样品中Br2浓度和氧含量的不同,快组分的寿命约为6ns,慢组分的寿命约为20ns。较慢的分量被分配给A'态的衰变。根据热光栅的振幅,估计A'态形成的量子产率为0.33+0.03。测量到的A’态衰减率的Stern-Volmer图,包括近红外荧光和光热光栅测量的结果,表明在低浓度下A’态的猝灭首先以扩散限制速率进行,在高浓度下变为非扩散限制速率。还讨论了随浓度增加淬火速率降低的可能机理。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Relaxation and Quenching of Excited States of Br2 in CC14 Studied by Photothermal Gratings Combined with Near-IR Fluorescence
Relaxation and quenching of excited states of Br2 in CC14 is studied by time-resolved photothermal grating combined with near-IR fluorescence. A slow rise in diffraction transient signals from photothermal gratings, due to nonradiative relaxation of excited states, is observed for Br2 in CC14. Near-IR fluorescence measurement reveals that there are two decay components; the fast component has a lifetime about 6 ns, and the slower component has a lifetime around 20 ns, depending on Br2 concentration and oxygen content in the sample. The slower component is assigned to the decay of A' state. From the amplitudes of thermal grating, the quantum yield of the A' state formation is estimated to be 0.33+0.03. Stern-Volmer plot of the measured decay rate of A' state, including results obtained from both near-IR fluorescence and photothermal grating measurement, suggests that quenching of A' state proceeds initially at diffusion-limited rate at low concentration and reduces to nondiffusion-limited at higher concentration. Possible mechanisms for the observed decrease of quenching rate as concentration increases are also discussed.
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