Formation of nitric acid hydrates at cryogenic temperatures
Denitrification of the stratosphere plays an important role in the annual springtime ozone depletion ("ozone hole") over Antarctica. Field measurements suggest that chemical reactions which are responsible for the removal of NOy reservoir species such as N2O5 from the gas phase take place...
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ftawi:oai:epic.awi.de:13971 2023-09-05T13:15:15+02:00 Formation of nitric acid hydrates at cryogenic temperatures Peil, S. Schrems, Otto 1993 https://epic.awi.de/id/eprint/13971/ https://hdl.handle.net/10013/epic.24323 unknown Peil, S. and Schrems, O. (1993) Formation of nitric acid hydrates at cryogenic temperatures , European Research Conference on Chemistry and Physics of Matrix Isolated Species, 17-22 July, Helsinki, Finland. . hdl:10013/epic.24323 EPIC3European Research Conference on Chemistry and Physics of Matrix Isolated Species, 17-22 July, Helsinki, Finland. Conference notRev 1993 ftawi 2023-08-22T19:50:53Z Denitrification of the stratosphere plays an important role in the annual springtime ozone depletion ("ozone hole") over Antarctica. Field measurements suggest that chemical reactions which are responsible for the removal of NOy reservoir species such as N2O5 from the gas phase take place at the cold surface of polar stratospheric clouds (PSC's) and aerosol particles in the stratosphere.PSC's of type I can form 5-7 K above the frost point of ice in the winterly stratosphere and are believed to be particles consisting of a nitric acid hydrate, probably the nitric acid trihydrate (NAT). PSC's of type II on the other hand consist of water ice particles.In order to study reactions on PSC model surfaces in the laboratory we have investigated the different amorphous and crystalline nitric acid hydrates which can be formed at low temperatures. Thin solid films of these hydrates have been prepared and have been characterized by recording their RAIR (Reflection Absorption InfraRed) spectra. It was found that all the different hydrates are metastable concerning irreversible, thermically inducable transformation to beta-NAT, which is one of the two possible modifications NAT can form.We have then studied the reaction of N2O5 with water ice, a PSC type II model surface at low temperatures. Above 150 K reaction takes place which rapidly produces HNO3, which is incorporated into the ice solely as alpha- or beta-NAT, depending on temperature. In the polar stratosphere PSC type II surfaces (water ice) might be converted to PSC type I (NAT) surfaces by this process. Conference Object Antarc* Antarctica Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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Denitrification of the stratosphere plays an important role in the annual springtime ozone depletion ("ozone hole") over Antarctica. Field measurements suggest that chemical reactions which are responsible for the removal of NOy reservoir species such as N2O5 from the gas phase take place at the cold surface of polar stratospheric clouds (PSC's) and aerosol particles in the stratosphere.PSC's of type I can form 5-7 K above the frost point of ice in the winterly stratosphere and are believed to be particles consisting of a nitric acid hydrate, probably the nitric acid trihydrate (NAT). PSC's of type II on the other hand consist of water ice particles.In order to study reactions on PSC model surfaces in the laboratory we have investigated the different amorphous and crystalline nitric acid hydrates which can be formed at low temperatures. Thin solid films of these hydrates have been prepared and have been characterized by recording their RAIR (Reflection Absorption InfraRed) spectra. It was found that all the different hydrates are metastable concerning irreversible, thermically inducable transformation to beta-NAT, which is one of the two possible modifications NAT can form.We have then studied the reaction of N2O5 with water ice, a PSC type II model surface at low temperatures. Above 150 K reaction takes place which rapidly produces HNO3, which is incorporated into the ice solely as alpha- or beta-NAT, depending on temperature. In the polar stratosphere PSC type II surfaces (water ice) might be converted to PSC type I (NAT) surfaces by this process. |
format |
Conference Object |
author |
Peil, S. Schrems, Otto |
spellingShingle |
Peil, S. Schrems, Otto Formation of nitric acid hydrates at cryogenic temperatures |
author_facet |
Peil, S. Schrems, Otto |
author_sort |
Peil, S. |
title |
Formation of nitric acid hydrates at cryogenic temperatures |
title_short |
Formation of nitric acid hydrates at cryogenic temperatures |
title_full |
Formation of nitric acid hydrates at cryogenic temperatures |
title_fullStr |
Formation of nitric acid hydrates at cryogenic temperatures |
title_full_unstemmed |
Formation of nitric acid hydrates at cryogenic temperatures |
title_sort |
formation of nitric acid hydrates at cryogenic temperatures |
publishDate |
1993 |
url |
https://epic.awi.de/id/eprint/13971/ https://hdl.handle.net/10013/epic.24323 |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
EPIC3European Research Conference on Chemistry and Physics of Matrix Isolated Species, 17-22 July, Helsinki, Finland. |
op_relation |
Peil, S. and Schrems, O. (1993) Formation of nitric acid hydrates at cryogenic temperatures , European Research Conference on Chemistry and Physics of Matrix Isolated Species, 17-22 July, Helsinki, Finland. . hdl:10013/epic.24323 |
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1776197069410664448 |