Abstract

Rotational lines of the S₁-S₀ band system of H₂CS have been recorded with an intracavity sub-Doppler technique at a resolution of 10 MHz. The spectra show numerous extra lines due to interactions of the S₁ levels with high rovibronic levels of the ground state, and to a lesser extent with levels of the T₁ state. In favorable cases it has been possible to extract coupling matrix elements from the data. The S₁-T₁ matrix elements are of the order of 1–0.1 cm^-1 while the S₁-S₀ matrix elements are much smaller with values from 6.5 × 10^-3 to 1.4 · 10^-3 cm^-1. The observed perturbations correlate well with observations of level specific anomalously long life times and reduced fluorescence yields in the isolated molecule. The interactions with ground state levels can be classified as step one in the progressive stages of interstate coupling leading to chaos in the optical spectrum of a small molecule.

© 1992 Optical Society of America