Open AccessBenzophenone Ultrafast Triplet Population: Revisiting the Kinetic Model by Surface-Hopping Dynamics
Author(s) -
Marco Marazzi,
Sebastian Mai,
Daniel RocaSanjuán,
Mickaël G. Delcey,
Roland Lindh,
Leticia González,
Antonio Monari
Publication year - 2016
Publication title -
the journal of physical chemistry letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.563
H-Index - 203
ISSN - 1948-7185
DOI - 10.1021/acs.jpclett.5b02792
Subject(s) - benzophenone , population , chemical physics , chemistry , spectroscopy , surface hopping , ultrafast laser spectroscopy , triplet state , excitation , photochemistry , kinetic energy , ab initio quantum chemistry methods , molecular dynamics , molecular physics , computational chemistry , molecule , physics , quantum mechanics , demography , organic chemistry , sociology
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.
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