Single-molecule pump-probe experiments reveal variations in ultrafast energy redistribution.
Single-molecule pump-probe experiments reveal variations in ultrafast energy redistribution.
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单分子泵浦探针实验揭示了超快能量重新分布的变化。
DOI：
10.1063/1.1940567
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
N. F. Hulst
中科院分区：
文献类型：
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作者：
Erik M. H. P. van Dijk;J. Hernando;M. Garcia;N. F. Hulst
单分子泵探针 (SM2P) 是一种基于荧光的新型技术，可在单分子水平上研究超快过程。利用 SM2P，我们观察到同一样品中化学性质相同的分子的能量重新分配时间存在很大变化（从 1 ps 到低于 100 fs）。将分子嵌入不同的基质中或改变激发波长不会导致平均重新分布时间发生显着变化。然而，化学性质不同的分子表现出不同的特征重新分布时间。因此，我们得出结论，用 SM2P 技术测量的过程主要是分子内能量重新分配，而不是分子间转移到周围基质。然而，基质负责诱导分子构象变化，从而影响电子模式和振动模式之间的耦合。这些构象变化是观察到的重新分布时间广泛分布的主要根源。
Single-molecule pump probe (SM2P) is a novel, fluorescence-based technique that allows the study of ultrafast processes on the single-molecule level. Exploiting SM2P we have observed large variations (from 1 ps to below 100 fs) in the energy redistribution times of chemically identical molecules in the same sample. Embedding the molecules in a different matrix or changing the excitation wavelength does not lead to significant changes in the average redistribution time. However, chemically different molecules exhibit different characteristic redistribution times. We therefore conclude that the process measured with the SM2P technique is dominated by intramolecular energy redistribution and not intermolecular transfer to the surrounding matrix. The matrix though is responsible for inducing conformational changes in the molecule, which affect the coupling between electronic and vibrational modes. These conformational changes are the main origin of the observed broad distribution of redistribution times.