Abstract

Electronically excited states lend themselves to time-resolved spectroscopic methods in which the flow of vibrational energy caused by intramolecular vibrational energy redistribution (IVR) can be observed. Although previous studies have provided important information on IVR lifetimes, they have been unable to identify the bath or ‘dark’ states into which population is transferred by IVR. If such an identification can be made, much useful information could potentially be gleaned into the coupling between the vibrational modes and the mechanisms by which vibrational energy flows around the molecular system. Although such information may in principle be deduced from a high-resolution frequency-resolved study of the S₀ ↔ S₁ transition, experiments with the necessary resolution to do this at the required wavelengths generally concentrate on a small energy region because of the host of resolved eigenstates. The use of a time-resolved photoionization technique enables in principle not only precise control of the time delay between preparation and examination of the S₁ level of interest, but also identification of the dark states involved in the IVR process via their photoelectron spectra.

© 2005 Optical Society of America