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Monotonic Increase of Nitrite Yields in the Photolysis of Nitrate in Ice and Water between 238 and 294 K

Dubowski, Yael and Colussi, A. J. and Boxe, Christopher and Hoffmann, M. R. (2002) Monotonic Increase of Nitrite Yields in the Photolysis of Nitrate in Ice and Water between 238 and 294 K. Journal of Physical Chemistry A, 106 (30). pp. 6967-6971. ISSN 1089-5639. https://resolver.caltech.edu/CaltechAUTHORS:20150623-154757422

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Abstract

The quantum yield, φ, of nitrite formation in the 302 nm band photolysis of fluid or frozen aqueous nitrate solutions increases monotonically with temperature over the range 238−294 K. The presence of formate increases φ 5-fold but does not modify its temperature dependence. Considering that the detection of nitrite as a product is only possible after the initial photofragments (NO_2^- + O) escape the solvent cage and that the diffusivity of ice, D_(ice), is about 6 orders of magnitude smaller than that of supercooled water, D_(aq), at the same temperature, we infer that nitrate photodecomposition takes place in similar liquidlike media at all temperatures. We found that the nitrite dispersed into the bulk is subsequently degraded by OH radicals, another primary photoproduct that can be scavenged by formate. The fact that experimental φ values in ice are actually larger than those derived from linear φ vs D_(aq)T^(1/2) extrapolation of aqueous phase data, as expected for cage processes in homogeneous media, suggests that the photochemically relevant properties of the quasi-liquid layer covering ice below the normal melting point resemble those of bulk supercooled water, but other effects, such as the dissipation of excess photon energy into the medium, may also play a role.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp0142942DOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp0142942PublisherArticle
ORCID:
AuthorORCID
Colussi, A. J.0000-0002-3400-4101
Hoffmann, M. R.0000-0002-0432-6564
Additional Information:© 2002 American Chemical Society. Received: November 20, 2001; In Final Form: April 11, 2002.
Issue or Number:30
Record Number:CaltechAUTHORS:20150623-154757422
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150623-154757422
Official Citation:Monotonic Increase of Nitrite Yields in the Photolysis of Nitrate in Ice and Water between 238 and 294 K Yael Dubowski, A. J. Colussi, Christopher Boxe, and M. R. Hoffmann The Journal of Physical Chemistry A 2002 106 (30), 6967-6971 DOI: 10.1021/jp0142942
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58482
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:28 Jul 2015 20:33
Last Modified:03 Oct 2019 08:36

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