Ultrafast photoisomerization in DCM dye observed by new femtosecond Raman spectroscopy

Ultrafast trans-cis photoisomerization in DCM solutions has been investigated using new time-resolved Raman spectroscopy. The new method measures stimulated Raman scattering in photoinduced transient species using a Raman pump pulse with narrow bandwidth and a femtosecond supercontinuum probe pulse. The temporal and spectral resolutions obtained in this study are 250 fs and 25 cm(-1), respectively. The observed Raman signals are separated to two groups from the temporal dependence and assigned to an intermediate state between trans- and cis-forms and a charge-transfer state in DCM. (C) 2000 Elsevier Science B.V. All rights reserved.