Parahalogenated phenols accelerate the photochemical release of nitrogen oxides from frozen solutions containing nitrate

Article abstract of DOI:10.1021/jp210249t

The photolysis of nitrate anion (NO₃^-) contained in surface ice and snow can be a regionally significant source of gas-phase nitrogen oxides and affect the composition of the planetary boundary layer. In this study, the photochemical release of nitrogen oxides from frozen solutions containing NO₃^- in the presence of organic compounds was investigated. Gas-phase nitrogen oxides were quantified primarily by NO-O ₃ chemiluminescence detection of NO and NO_y (=NO + NO ₂ + HONO + HNO₃ + -PAN + -AN...) and cavity ring-down spectroscopy of NO₂ and total alkyl nitrates (-AN). The photochemical production of gas-phase NO_y was suppressed by the presence of formate, methanesulfonate, toluene, or phenol. In contrast, para-halogenated phenols (in the order of Cl > Br > F) promoted the conversion of NO ₃^- to gas-phase NO_y, rationalized by acidification of the ice surface.