Journal of Physical Chemistry A, Vol.116, No.24, 5923-5931, 2012
Parahalogenated Phenols Accelerate the Photochemical Release of Nitrogen Oxides from Frozen Solutions Containing Nitrate
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 NOy (=NO + NO2 + HONO + HNO3 + Sigma PAN + Sigma AN ...) and cavity ring-down spectroscopy of NO2 and total alkyl nitrates (Sigma AN). The photochemical production of gas-phase NOy 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 NO3- to gas-phase NOy, rationalized by acidification of the ice surface.