Cross Relaxation Effect in the Polarization Spectroscopy of Condensed Phases

Abstract

A detailed theoretical analysis is given for the ultrafast relaxation study using polarization spectroscopy in the frequency domain to clarify the effect of cross relaxation on the measured results. It is shown that the calculated nonlinear spectral response function reflects the inhomogeneous width rather than the homogeneous one if the rate of cross relaxation of the transition becomes so singnificant. This prevents us from precise determination of phase relaxation Time T 2 of the transition by the stationary polarization spectroscopy. It is further shown that the cross relaxation effect onto the measured spectral response function can effectively be diminished by introducing a partially transient condition. An experiment using picosecond light pulses is presented to demonstrate this fact.