Observation of gas-phase peroxynitrous and peroxynitric acid during the photolysis of nitrate in acidified frozen solutions

Abstract The photolysis of nitrate embedded in ice and snow can be a significant source of volatile nitrogen oxides affecting the composition of the planetary boundary layer. In this work, we examined the nitrogen oxides evolved from irradiated frozen solutions containing nitrate. Products were monitored by cavity ring-down spectroscopy (CRDS), NO-O 3 chemiluminescence (CL), and chemical ionization mass spectrometry (CIMS). Under acidic conditions, the nitrogen oxides volatilized were mainly in the form of NO z , i.e., nitrous (HONO), nitric (HONO 2 ), peroxynitrous (HOONO), and peroxynitric acid (HO 2 NO 2 ). Identification of acidic nitrogen oxides by CIMS and possible HOONO, HONO 2 and HO 2 NO 2 formation pathways are discussed.