X-RAY PHOTOELECTRON SPECTROSCOPIC STUDIES OF THE HETEROGENOUS REACTION OF GASEOUS NITRIC-ACID WITH SODIUM-CHLORIDE - KINETICS AND CONTRIBUTION TO THE CHEMISTRY OF THE MARINE TROPOSPHERE

We report here the first measurement of the reaction probability (phi) at 298 K for the reaction (1) HNO3(g) + NaCl(s) --- > HCl(g) + NaNO3( s), phi = (4 +/- 2) x 10(-4), which was determined using X-ray photoel ectron spectroscopy to follow the formation of nitrate on the surface of single crystals of NaCl. Along with recent kinetic data for the rea ction N2O5(s) + NaCl(s) --- > ClNO2(s) + NaNO3(s), we show that in the dark with typical relative concentrations of N2O5 and HNO3, the N2O5, reaction should be competitive with, and may exceed, that of HNO3. Th e reactions of NO2 and ClONO2 with NaCl are expected to be much less i mportant. Thus, the tropospheric production of chlorine atoms via phot olysis of ClNO2 from the N2O5 reaction is anticipated, which has the p otential to impact the ozone balance in the troposphere.