Measurements of zero kinetic energy (ZEKE) photoelectron spectra were carried out with nanosecond lasers for trans-stilbene in a free jet expansion, by means of two-color (1 + 1′) REMPI via several S1 vibrational levels. A series of observed ZEKE photoelectron spectra of trans-stilbene show well-resolved low-frequency vibrational structure due to the cation in the energy region up to 1500 cm-1. The adiabatic ionization potential of trans-stilbene has been determined as 61 748 ± 4 cm-1. Vibrational frequencies of 290, 208, 49, and 39 cm-1 have been assigned to the vibrational modes 24+, 25+, 36+, and 37+ of the cation, respectively. It has also been found that the observed congested vibrational bands originate not only from the initially prepared S1 levels but also from relaxed S1 vibrational levels produced by intramolecular vibrational redistribution (IVR). The present IVR results are consistent with an available picosecond laser dispersed fluorescence study. The present work also clearly demonstrates that (1 + 1′) ZEKE photoelectron spectroscopy has sufficient capability for studying the dynamics of electronically excited neutral molecules.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry