Benzophenone Ultrafast Triplet Population: Revisiting the Kinetic Model by Surface-Hopping Dynamics.
Benzophenone Ultrafast Triplet Population: Revisiting the Kinetic Model by Surface-Hopping Dynamics.
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DOI：
10.1021/acs.jpclett.5b02792
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发表时间：
2016-02-18
期刊：
影响因子：
--
通讯作者：
Monari A
中科院分区：
文献类型：
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作者：
Marazzi M;Mai S;Roca-Sanjuán D;Delcey MG;Lindh R;González L;Monari A
用表面跃迁从头算分子动力学方法研究了光敏化有机分子二苯甲酮的光化学行为。在激发后的前600fs内，发现不同的机制是相关的；长期争论的低三重态布居的直接机制(S1→T1)和间接机制(S1→T2→T1)都是可能的，而后者是普遍存在的。此外，我们建立了两个三重态之间的动态平衡的存在，这是以前从未观察到的。这一事实意味着很大一部分总体存在于T2，最终允许人们重新审视由瞬变吸收光谱提出的通常的光谱分配。这一发现对光催化和DNA损伤研究特别感兴趣，因为原则上，T1和T2通道都可用于二苯甲酮介导的光诱导能量向DNA的转移。
The photochemistry of benzophenone, a paradigmatic organic molecule for photosensitization, was investigated by means of surface-hopping ab initio molecular dynamics. Different mechanisms were found to be relevant within the first 600 fs after excitation; the long-debated direct (S1 → T1) and indirect (S1 → T2 → T1) mechanisms for population of the low-lying triplet state are both possible, with the latter being prevalent. Moreover, we established the existence of a kinetic equilibrium between the two triplet states, never observed before. This fact implies that a significant fraction of the overall population resides in T2, eventually allowing one to revisit the usual spectroscopic assignment proposed by transient absorption spectroscopy. This finding is of particular interest for photocatalysis as well as for DNA damages studies because both T1 and T2 channels are, in principle, available for benzophenone-mediated photoinduced energy transfer toward DNA.