Heterogeneous Chemistry of Nitryl Halides in Relation to Tropospheric Halogen Activation

The heterogeneous chemistry of nitryl chloride and nitryl bromide by salt containing solutions was studied as a function of temperature in the range from 275 to 293 K with the wetted-wall flowtube combined with FTIR and mass spectrometry detection. Uptake coefficients and values of the product Hk^1/2 on these saline solutions have been determined. For nitryl halides interacting with NaI and NaBr solutions, the values of the product Hk^1/2 are respectively 4384.7±326.7 and 103.1±18.7 M atm^-1 s^-1/2 for nitryl chloride at 275 K and 544.2±94.7 and 47.7±15.2 M atm^-1 s^-1/2 for nitryl bromide at 278 K. When reacting with NaI or NaBr solutions, these heterogeneous reactions release, as major products, the molecular forms of the halogen i.e., respectively I₂ and Br₂. A simplified reaction scheme explaining the formation of these products is presented and is inserted into a model simulating the chemistry in the marine boundary layer. The modelling effort showed Cl and BrO atoms concentrations up to 5×10⁴ and 1.8×10⁶ molecules cm^-3 respectively, which are comparable to values actually measured in field campaigns.     

表面活性剂对钪－铜铁试剂络合吸附波的增敏效应

探讨了各种类型的表面活性剂对Ｓｃ－铜铁试剂体系的增敏效应；观察到在ｐＨ９．０的ＮＨ＿４ＯＨ－ＮＨ＿４Ｃｌ缓冲介质中，溴化十四烷基三甲铵使该体系催化波灵敏度提高了２５倍。峰电位在－１．５０Ｖ（ｕｓ．Ａｇ／ＡｇＣｌ），峰高与Ｓｃ浓度在２～４０ｎｇ／ｍｌ呈线性关系，检出限１ｎｇ／ｍｌ；用拟定的方法测定了岩石样品中的痕量Ｓｃ；并对其极谱性质和表面活性剂增敏机理进行了探讨。