Benzophenone Ultrafast Triplet Population: Revisiting the Kinetic Model by Surface-Hopping Dynamics

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• 作者：Marco Marazzi ; Sebastian Mai ; Daniel Roca-Sanjuán ; Mickaël G. Delcey ; Roland Lindh ; Leticia González ; Antonio Monari
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：February 18, 2016
• 年：2016
• 卷：7
• 期：4
• 页码：622-626
• 全文大小：347K
• ISSN：1948-7185

文摘

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.