Formation and Dissociation of N3 in Icy N2 with Far-ultraviolet Light

During photoexcitation of icy N-2 at 121.6 nm from a synchrotron source, emission lines in the vibronic progression of the Vegard-Kaplan system, A (3)Sigma(+)(u) -> X-2(1)Sigma(+)(g), for N-2 were concurrently observed in the wavelength range 210-430 nm; emission lines of N (P-2 -> D-2) and N (D-2 -> S-4) were recorded in the wavelength range 460-1100 nm. After irradiation of icy N-2 at 121.6 nm, the characteristic infrared absorption lines of N(3 )radical in vibrational mode nu(3) appeared at 1652.6 and 1657.8 cm(-1). When the irradiated icy sample containing N-3 radical was subsequently subjected to photolysis at 190 nm, only emission from N (D-2 -> S-4) was concurrently recorded; the IR absorption lines of N-3 vanished. The result indicates that N-3 radical in icy N-2 can be dissociated into the N (D-2) atom and N-2 (X (1)Sigma(+)(g)) molecule with light at 190 nm. Our work thus has ramifications for nitrogen transformation in cold astrophysical environments.