Magnetic-field and time-resolved studies of the electronic spectrum of HNO

Abstract

High-resolution laser-induced fluorescence excitation spectra of HNO have been recorded using both c.w. and pulsed dye lasers. These spectra reveal numerous frequency perturbations, often associated with marked intensity anomalies. All the branches studied were found to be perturbed to some degree with little regularity to the perturbations. The widths of some of the perturbed lines, and of many apparently unperturbed lines, have been found to be sensitive to a magnetic field. Timeresolved measurements yield a mean zero-pressure excited-state lifetime of 23 µs, and collisional quenching rates varying from (1.1 to 15)× 10^–10 cm³ molecule^–1 s^–1. These studies reveal that the intensity anomalies arise through selective higher quenching of perturbed levels, coupled with fast rotational-energy transfer. These aspects are discussed in terms of interaction between the levels of the excited Ã, ¹A″ state and high levels of the ground X, ¹A′ state, with further perturbations from the ã, ³A″ state.