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

Abstract

Abstract During photoexcitation of icy N2 at 121.6 nm from a synchrotron source, emission lines in the vibronic progression of the Vegard–Kaplan system, A , for N2 were concurrently observed in the wavelength range 210–430 nm; emission lines of N (2P → 2D) and N (2D → 4S) were recorded in the wavelength range 460–1100 nm. After irradiation of icy N2 at 121.6 nm, the characteristic infrared absorption lines of N3 radical in vibrational mode ν 3 appeared at 1652.6 and 1657.8 cm−1. When the irradiated icy sample containing N3 radical was subsequently subjected to photolysis at 190 nm, only emission from N (2D → 4S) was concurrently recorded; the IR absorption lines of N3 vanished. The result indicates that N3 radical in icy N2 can be dissociated into the N (2D) atom and N2 ( ) molecule with light at 190 nm. Our work thus has ramifications for nitrogen transformation in cold astrophysical environments.