jz9b03488_si_001.pdf (1014.51 kB)
Non-Born–Oppenheimer Molecular Dynamics Observed by Coherent Nuclear Wave Packets
journal contribution
posted on 2020-01-16, 19:39 authored by JunWoo Kim, Chul Hoon Kim, Christian Burger, Myeongkee Park, Matthias F. Kling, Dong Eon Kim, Taiha JooThe
reaction dynamics of a photochemical reaction is typically
described by reaction coordinates based on the Born–Oppenheimer
(BO) approximation. A strong interaction between electrons and nuclei,
conventionally occurring at conical intersections, however, breaks
the BO approximation and has major consequences for the efficiency
of a photochemical reaction. Despite its importance, related studies
into the non-BO dynamics are scarce. Here, we investigate the non-BO
dynamics of excited-state intramolecular proton transfer (ESIPT) occurring
in 10-hydroxybenzo[h]quinoline (HBQ). Two coherent
vibrational modes at 237 and 794 cm–1 representing
molecular dynamics on a diabatic surface in HBQ are identified by
a wave packet analysis based on a transient absorption measurement
with a time resolution of 11 fs and with a density functional theory-based
model calculation. It is also revealed that the strong Coulomb field
effect in HBQ leads to the completion of ESIPT within about two cycles
of the OH stretching mode. The work paves the way for time-domain
studies of molecular dynamics beyond the BO approximation in other
photochemical reactions.