THE (N, 3S) RYDBERG STATE IN DEUTERATED ALDEHYDES - JET-COOLED MPI SPECTRA OF THE PROPANAL ISOTOPOMERIC SERIES

We report here the results of our investigation into the vibrational s tructure in the (n, 3s) Rydberg state of various isotopomers of propan al via 2 + 1 multiphoton ionization (MPI) spectroscopy in both a stati c cell and a supersonic expansion. A vibronic analysis of the 3s <-- n transition has resulted in an assignment for a number of excited stat e vibrational frequencies. Most structure is due to the cis conformer with three features identified as belonging to the higher energy skew, conformer. The d1-methyl- and d2-methyl-deuterated propanal isotopome rs exhibit almost-equal-to 18 cm-1 splitting of all peaks due to the o ccurrence of symmetric and asymmetric methyl rotamers. (C) 1994 Academ ic Press, Inc.