Molecular twisting and relaxation in the excited state of triarylpyrylium cations
Journal
Journal of Physical Chemistry A
Journal Volume
106
Journal Issue
38
Pages
8864-8869
Date Issued
2002
Author(s)
Abstract
Excited-state twisting and relaxation of triarylpyrylium cations with various substituents attached to different parts of the molecule were studied by means of femtosecond pump−probe absorption spectroscopy and modeled numerically. The model was based on calculations of the population evolution on the excited- and ground-state potential surfaces, which are significantly different for nonstabilized and stabilized states because of the essential angular dependence of the stabilization energy. The modeling shows that a broad population distribution along the twisting angle in the ground state is transferred to the excited state, causing strong fluorescence broadening, while competition between the excited-state twisting and solvation determines a subsequent reaction path. The internal conversion rate is determined by the energy gap law and, depending on the attached substituents, is governed either by twisting or by solvation processes.
SDGs
Type
journal article