Direct Observation of Molecular Structural Change during Intersystem Crossing by Real-Time Spectroscopy with a Few Optical Cycle Laser

Abstract

Ultrafast spectroscopy by a sub-5 fs pulse laser was applied to the simultaneous study of electronic relaxation and vibrational dynamics in Ru(II)(TPP)(CO). The electronic lifetimes of (1)Q(x(1,0))(pi,pi*) and (1)Q(x(0,0))(pi,pi*) were determined to be 230 +/- 70 fs and 1150 +/- 260 fs, respectively. The spectrogram shows the time dependent changes in the vibrational spectrum associated with the spin state change from the Franck-Condon state in the excited singlet state to the triplet state via the curve crossing point between the singlet and triplet potential surfaces. The time constant of the intersystem crossing process was determined to be about 1.0 ps from observed electronic relaxation and vibrational dynamics reflecting the transition from the singlet to triplet electronic excited state.