Resonance Raman intensities of perdeuterated cis-stilbene were measured usi
ng excitation at 266 nm. For the six analysed bands at 1612, 1564 1537,1372
, 1325 and 958 cm(-1), no large changes in intensity distribution relative
to the parent compound were found in accordance with the scrambling coeffic
ients showing that the corresponding modes v(7), v(8), v(9) v(10), v(11) an
d v(15) of d(12)-cis-stilbene have all of the Raman activity. The S-1 equil
ibrium geometry and vibrational force field for cis-stilbene were calculate
d at the CIS/6-31G(d) level and the vibrational assignment for the parent c
ompound and some of its symmetrically substituted isotopomers is considered
. The obtained excited-state geometry distortions are large, preventing the
use of a simple displacement equation for relative Raman intensities. Ther
efore, in their determination the gradients of the Sr state, potential ener
gy surfaces calculated at the ground-state geometry were also used. Even in
its simplest form this approach reproduces the experiment fairly reasonabl
y. Copyright (C) 2001 John Wiley & Sons, Ltd.