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| Titel |
The adsorption of nitrogen oxides on crystalline ice |
| VerfasserIn |
T. Bartels, B. Eichler, P. Zimmermann, H. W. Gäggeler, M. Ammann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 2, no. 3 ; Nr. 2, no. 3 (2002-09-20), S.235-247 |
| Datensatznummer |
250000619
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| Publikation (Nr.) |
 copernicus.org/acp-2-235-2002.pdf |
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| Zusammenfassung |
| The partitioning of nitrogen oxides between ice and air is of importance to
the ozone budget in the upper troposphere. In the present study, adsorption
of nitrogen oxides on ice was investigated at atmospheric pressure using a
chromatographic technique with radioactively labelled nitrogen oxides at low
concentrations. The measured retentions solely depended on molecular adsorption and were not influenced by dimerisation, formation of encapsulated
hydrates on the ice surface, dissociation of the acids, nor by migration into
a quasi-liquid layer or grain boundaries. Based on the chromatographic retention and the model of thermo-chromatography, the standard adsorption
enthalpy of -20 kJ mol-1 for NO, -22kJ mol-1 for NO2,
-30kJ mol-1 for peroxyacetyl nitrate, -32kJ mol-1 for
HON} and -44 kJ mol-1 for HNO3 was calculated. To perform those calculations
within the model of thermo-chromatography, the standard adsorption entropy
was calculated based on statistical thermodynamics. In this work, two different choices of standard states were applied, and consequently different
values of the standard adsorption entropy, of either between -39 kJ mol-1 and
-45kJ mol-1, or -164 kJ mol-1 and -169 kJ mol-1
for each nitrogen oxide were derived. The standard adsorption enthalpy was identical for both standard
adsorption entropies and thus shown to be independent of the choice of standard state. A brief outlook on environmental implications of our findings
indicates that adsorption on ice might be an important removal process of
HNO3. In addition, it might be of some importance for HONO and peroxyacetyl nitrate and irrelevant for
NO and NO2. |
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