Interaction of peroxynitric acid with solid H_2O ice
The uptake of peroxynitric acid (PNA), HO_2NO_2 or HNO_4, on solid H_2O ice at 193 K (−80°C) was studied using a fast flow‐mass spectrometric technique. An uptake coefficient of 0.15 ± 0.10 was measured, where the quoted uncertainty denotes 2 standard deviations. The uptake process did not result in the production of gas phase products. The composition of the condensed phase was investigated using programmed heating (3 K min^(−1)) of the substrate coupled with mass spectrometric detection of desorbed species. Significant quantities of HNO_4 and HNO_3 desorbed from the substrates at temperatures above 225 K and 246 K, respectively. The desorbed HNO_3, which was less than 9% of the desorbed HNO_4 and remained unchanged upon incubation of the substrate, was likely due to impurities in the HNO_4 samples rather than reaction of HNO_4 on the substrate. The onset temperatures for HNO_4 desorption increased with increasing H_2O to HNO_4 ratios, indicating that HNO_4, like HNO_3, tends to be hydrated in the presence of water. These observations suggest possible mechanisms for removal of HNO_4 or repartitioning of total odd nitrogen species in the Earth's upper troposphere and stratosphere.
© 1996 by the American Geophysical Union. Paper number 96JD0065. Received August 1, 1995; revised December 13, 1995; accepted December 13, 1995. The research described in this paper was carried out at Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We thank G. T. Toon, M. R. Gunson, and R. J. Salawitch for providing their unpublished results, R. Zhang, M.-T. Leu, and R. J. Salawitch for helpful discussion on our results, and R. D. May for facility assistance in preparing HNO_4.
||1.0 MB||Preview Download|