Fourier-transform electronic spectroscopy in the near-infrared: Torsional barrier of the Ā 1A″ state of nitrosobenzene

Abstract

The Fourier-transform absorption spectrum of nitrosobenzene vapour in the near-infrared has been recorded, and the vibrational bands near the 869 nm electronic origin of the Ā 1A″ ← X̄ 1A′ (n,π *) transition have been re-analysed. The prominent torsional structure observed is shown to represent sequence transitions in the torsional mode. Electronic excitation leads to an increase of the V 2 barrier hindering internal rotation from roughly 1300 cm −1 in the ground to 2500 cm −1 in the (n,π *) excited state.