A study of the NO radical with PE and CIS spectroscopy: investigation of NO(b³Π, 3p) and NO(b³Π, 4p) Rydberg states

Abstract

Angle resolved constant-ionic-state (CIS) and photoelectron (PE) spectra have been recorded for the NO radical from 13.2 to 30.0 eV. CIS spectra obtained for selected vibrational components of the first PE band in the photon energy range 13.5–15.7 eV are dominated by a sharp, intense structure arising from 5σ → np Rydberg resonances, which are parts of series which converge to NO⁺(b³Π). Spectra of the first PE band of NO were recorded at the observed resonance photon energies to study the effect on the PE vibrational envelopes and the asymmetry parameter β. The evidence obtained, supported by results of Franck–Condon simulations, has allowed assignment of the bands in the CIS spectrum associated with NO(b³Π, 3p) and NO(b³Π, 4p) resonances. This has led to a correction of some of the published assignments of these bands, which have been observed by other methods. A 2π → kσ shape resonance has also been observed centred at 14 eV and its effect on the vibrational envelope and asymmetry parameter of the first PE band has been investigated.