TRANS-STILBENE - A RIGID, PLANAR ASYMMETRIC-TOP IN THE ZERO-POINT VIBRATIONAL LEVELS OF ITS S0 AND S1 ELECTRONIC STATES

Resolved rotational structure has been observed in the fluorescence excitation spectrum of the 000 band in the S1 ← S0 electronic transition of trans-stilbene (tS) in the collision-free environment of a molecular beam. Analysis of this structure yields rotational constants for the S0 and S1 states, their inertial defects, and the orientation of the optical transition moment in the molecular frame. The results demonstrate that tS is a rigid, planar asymmetric top in the zero-point vibrational levels of both electronic states. © 1990 American Chemical Society.