FAR ULTRAVIOLET ABSORPTION SPECTRA OF N₃AND N₂⁺GENERATED BY ELECTRONS IMPACTING GASEOUS N₂

Abstract

Electron bombardment of gaseous N2 produces N2+ and N3, which are subsequently trapped in the N2 matrix at 10 K. Both the infrared and ultraviolet absorption spectra of the matrix sample at various stages of electron irradiation were recorded. Apart from a progression observed below 192 nm, with intervals ∼900 cm−1, corresponding to the transition of D 2Πg ← X 2Σg+ of N2+, three new progressions were recorded in the range 225–192 nm, with intervals ∼1000 cm−1, that correlated well with variations in intensities of the electronic absorption band of N3 at 272.7 nm; an absorption coefficient of 3.76 × 10−17 cm molecule−1 for the transition A2Σu+← X2Πg of N3 was estimated for the first time. These newly observed progressions were characterized and the vertical excitation energy and oscillator strength were calculated using time-dependent, density-functional theory. This was based on assigning the three progressions to electronic transitions of N3 from the ground state to 2 2Πu, 1 2Σg+, and 1 2Σg−, respectively.