Js. Baskin et al., FEMTOSECOND REAL-TIME PROBING OF REACTIONS .20. DYNAMICS OF TWISTING,ALIGNMENT, AND IVR IN THE TRANS-STILBENE ISOMERIZATION REACTION, Journal of physical chemistry, 100(29), 1996, pp. 11920-11933
The femtosecond real-time dynamics of the isomerization reaction of tr
ans-stilbene under collisionless conditions are studied using (2+1) re
sonance-enhanced multiphoton ionization (REMPI) and femtosecond deplet
ion spectroscopy (FDS) in a pump-probe scheme. The observed transients
reflect the macroscopic sample anisotropy decay (rotational coherence
) and intramolecular vibrational energy redistribution (IVR) as well a
s the ethylenic twisting isomerization reaction. Polarization-resolved
measurements are performed to isolate the influence of rotational dyn
amics, and the measured anisotropy decay is compared with theoretical
calculations of rotational coherence at room temperature. The IVR and
nonradiative (isomerization) processes of trans-stilbene are studied a
s a function of S-1 excess vibrational energy up to similar to 6500 cm
(-1). These results are compared with previous measurements of trans-s
tilbene under collisionless conditions and with predictions of RRK and
RRKM theories.