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Uptake of Formic Acid on Thin Ice Films and on Ice Doped with Nitric Acid between 195 and 211 K.
MedLine Citation:
PMID:  20960493     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
The adsorption of formic acid on thin ice films and on ice doped with nitric acid (1.96, 7.69 and 53.8 wt %) is studied as a function of temperature T=195-211 K and gas concentration (0.33-10.6)×10(11) molecule cm(-3). Experiments are performed in a Knudsen flow reactor coupled with a quadrupole mass spectrometer. The initial uptake coefficients γ are strongly and inversely dependent on the ice temperature. Initial uptake is determined at low surface coverages and ranges from (0.65-3.78)×10(-3). The adsorption uptake of formic acid on pure ice films and on ice lightly doped with HNO(3) is a reversible process, and the adsorption isotherms exhibit Langmuir behaviour. N(max)(1) is (2.94±0.67)×10(14) molecule cm(-2), in good agreement with previous measurements. The temperature dependence of K(Lin) is very well represented by the expression: K(Lin)(1)=(1.43±0.32)×10(-8) exp[(4720±520)/T] cm(3) molecule(-1); the quoted uncertainty is at the 95 % level of confidence and includes systematic uncertainties. Formic acid uptakes on ice films highly doped with HNO(3) (53.8 wt %) are two orders of magnitude higher than those measured on pure ice films and irreversible, thus indicating the formation of a supercooled liquid layer on the ice films upon which dissolution of formic acid occurs. Finally, the atmospheric lifetime of formic acid due to heterogeneous loss on cirrus cloud ice particles and the removal of formic acid by adsorption are estimated under conditions related to the upper troposphere.
Authors:
Manolis N Romanias; Antonia G Zogka; Vassileios G Stefanopoulos; Vassileios C Papadimitriou; Panos Papagiannakopoulos
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Chemphyschem : a European journal of chemical physics and physical chemistry     Volume:  11     ISSN:  1439-7641     ISO Abbreviation:  Chemphyschem     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-14     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100954211     Medline TA:  Chemphyschem     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  4042-52     Citation Subset:  IM    
Affiliation:
Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete (Greece), Fax: (+30) 2810-545-001.
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