Selenoformaldehyde: Rotational analysis of the [formula omitted] 735 nm band system of H 2C 78Se, H 2C 80Se, and D 2C 80Se from high-resolution laser fluorescence excitation spectra

Abstract

High-resolution laser fluorescence excitation spectra of vibronic bands in the A ̃ 1A 2- X ̃ 1A 1 system of H 2C 78Se, H 2C 80Se, and D 2C 80Se have been observed with Doppler-limited resolution. Three bands have been analyzed, yielding upper state molecular constants and improved ground state constants. The electronic transition is shown to be singlet-singlet in nature and the band polarizations are consistent with previous vibronic assignments. Erratic perturbations are observed in all three bands. The derived excited state r 0 structure is similar to that of H 2CS, suggesting that selenoformaldehyde adopts a near-planar equilibrium structure in the excited state.