Ultrafast nonradiative relaxation dynamics of eumelanin
Ultrafast nonradiative relaxation dynamics of eumelanin
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DOI：
10.1021/jp004045y
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发表时间：
2001-04-12
影响因子：
3.3
通讯作者：
Simon, JD
中科院分区：
文献类型：
--
作者：
Nofsinger, JB;Ye, T;Simon, JD
利用简并泵浦-探测飞秒光谱技术研究了乌贼真黑素在紫外光A激发下的初级光动力学行为。在320、350和380 nm处激发和探测产生瞬态吸收，该瞬态吸收在仪器响应内上升，并以小于约50 fs的寿命衰减。在这个瞬态信号的快速衰减之后，观察到与基态吸收的漂白相关联的恢复动力学。瞬态泵浦探测数据进行比较，报告的光声和时间分辨发射数据。这种比较表明，占主导地位的非辐射过程真黑素是再填充的基态电子状态和时间常数的非指数衰减的发射和吸收数据与化学不同的物种。
Degenerate pump-probe femtosecond spectroscopy is used to examine the primary photodynamics of eumelanin from Sepia officinalis following UV-A excitation. Exciting and probing at 320, 350, and 380 nm produces a transient absorption that rises within the instrument response and decays with a lifetime less than approximately 50 fs. Following the rapid decay of this transient signal, the recovery dynamics associated with the bleaching of the ground-state absorption are observed. The transient pump-probe data are compared to reported photoacoustic and time-resolved emission data. This comparison shows the dominant nonradiative process in eumelanin is repopulation of the ground electronic state and that the time constants revealed by the nonexponential decays of the emission and absorption data are associated with chemically distinct species.