GROUND-STATE IVR OF JET-COOLED P-ALKYLPHENOLS AND P-ALKYLANILINES STUDIED BY STIMULATED-EMISSION ION DIP AND STIMULATED RAMAN-UV OPTICAL DOUBLE-RESONANCE SPECTROSCOPIES

Stimulated emission ion dip (SEID) and stimulated Raman-UV optical double-resonance spectroscopies have been applied to study the intramolecular vibrational redistribution (IVR) of jet-cooled p-alkylphenols and p-alkylanilines in the S0 state. The IVR rate constant has been estimated vs the alkyl chain length (from methyl group to hexyl group) and vibrational energy (from 500 to 1500 cm-1). The vibrational modes excited were those mainly localized in the benzene ring. The ground-state IVR rate constants estimated from SEID spectroscopy were found to be similar in magnitude with those in the S1 state that were estimated by the dispersed fluorescence spectra. The decay of the vibrationally excited molecules in S0 was also measured using stimulated Raman-UV optical double-resonance spectroscopy. The obtained decay rates were found to be greatly different from those obtained by SEID spectroscopy. The difference is explained in terms of intermediate coupling case for the observed IVR process.