冰雪表面HNO_3的紫外光解机理

UV photolysis of HNO_3 on the ice film

利用308 nm激光与cavity ring-down spectroscopy技术对HNO3的气相与冰表面光解进行了研究,考察了其光解量子产额与吸收系数,结果表明,.OH+NO2*是其光解反应的主要通道;HNO3在253 K、308 nm冰表面的吸收系数为(1.21±0.31)×10-18cm2.molecule-1,比其在气相的吸收系数(1.24±0.19)×10-21 cm.2molecule-1(295 K)及(8.50±0.24)×10-22cm.2molecule-1(253 K)均高约3个数量级;HNO3在253K冰表面光解产生NO2*的量子产额为0.60±0.34.

Photolysis of nitric acid（HNO3） in the gas phase at 253 K and 295 K,on ice films at 253 K,was studied by using 308 nm excimer laser photolysis combined with cavity ring-down spectroscopy.The NO2＊ quantum yield and absorption cross section were directly measured.The results showed NO2＊ ＋· OH is a predominant photolysis pathway for the gas-phase photolysis of HNO3 at 308 nm.The 308 nm absorption cross section of HNO3 on ice films is（1.21±0.31）×10-18 cm2 · molecule-1 at 253 K which is about 3 orders of magnitude larger than its gas-phase cross section value of（1.24±0.19）×10-21 cm2 · molecule-1 at 295 K and（8.50±0.24） ×10-22 cm2 · molecule-1 at 253 K.The NO2＊ quantum yield from the HNO3 photolysis on ice films is 0.60±0.34 at 253 K.