Heterogeneous reactions of chlorine nitrate and hydrogen chloride on type I polar stratospheric clouds
- California Inst. of Tech., Pasadena (United States)
The heterogeneous reactions ClONO{sub 2} + NCl {yields} Cl{sub 2} + NHO{sub 3} (1) and ClONO{sub 2} + H{sub 2}O {yields} HOCl + HNO{sub 3} (2) on vapor-deposited NHO{sub 3}-H{sub 2}O ice substrates have been investigated at 196 K by using a fast-flow reactor coupled with a quadrupole mass spectrometer. The reaction probability for (1) is 0.10 {plus minus} 0.02 and independent of both the HNO{sub 3} and HCl concentrations in the substrate compositions studied. For (2), the reaction probability is approximately 1 {times} 10{sup {minus}5} near 53.8 wt% HNO{sub 3}, the composition of pure nitric acid trihydrate (NAT), and is about 1 {times} 10{sup {minus}3} at 46 wt% HNO{sub 3}. The sticking coefficient of HCl on these substrates was also found to be a strong function of the substrate composition, ranging from about 2 {times} 10{sup {minus}5} at NAT composition to 6 {times} 10{sup {minus}3} at 45 wt% HNO{sub 3}. The HNO{sub 3}-H{sub 2}O ice substrates were found to have large internal surface areas, and corrections for gas-phase diffusion within the porous ices were applied to observed loss rates. The large decrease in the HCl sticking coefficient and the reaction probability for (2) as the composition of pure NAT is approached from the water-enriched side can be semiquantatively explained in terms of a simple two-solid-phase model. Finally, the relation of these results to the depletion of polar ozone is discussed.
- OSTI ID:
- 7264101
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:20; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ATMOSPHERIC CHEMISTRY
CHEMICAL REACTIONS
CHEMISTRY
CHLORINE COMPOUNDS
CHLORINE NITRATES
CLOUDS
DATA
EARTH ATMOSPHERE
EXPERIMENTAL DATA
HALOGEN COMPOUNDS
HYDROCHLORIC ACID
HYDROGEN COMPOUNDS
ICE
INFORMATION
INORGANIC ACIDS
LAYERS
MASS SPECTROSCOPY
NITRATES
NITROGEN COMPOUNDS
NUMERICAL DATA
OXYGEN COMPOUNDS
OZONE LAYER
SPECTROSCOPY
STRATOSPHERE