FAR ULTRAVIOLET ABSORPTION SPECTRA OF N3 AND N2+ GENERATED BY ELECTRONS IMPACTING GASEOUS N2

Electron bombardment of gaseous N-2 produces N-2(+) and N-3, which are subsequently trapped in the N-2 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 similar to 900 cm(-1), corresponding to the transition of D-2 Pi(g) -> X (2)Sigma(+)(g) of N-2(+), three new progressions were recorded in the range 225-192 nm, with intervals similar to 1000 cm(-1), that correlated well with variations in intensities of the electronic absorption band of N-3 at 272.7 nm; an absorption coefficient of 3.76 x 10(-17) cm molecule(-1) for the transition A (2)Sigma(+)(u) -> X (2)Pi(g) of N-3 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 N-3 from the ground state to 2 (2)Pi(u), 1 (2)Sigma(+)(g), and 1 (2)Sigma(-)(g), respectively.