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Photochemical formation of large molecular weight oligomers from low-molecular weight keto-carbonyls in haze aerosol

Hoffmann, Michael R. and Rincon, Angela and Colussi, A. J. (2009) Photochemical formation of large molecular weight oligomers from low-molecular weight keto-carbonyls in haze aerosol. Geochimica et Cosmochimica Acta, 73 (13). A541. ISSN 0016-7037. http://resolver.caltech.edu/CaltechAUTHORS:20151214-130754417

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Abstract

The optical properties of the atmospheric aerosol play a fundamental role in the Earth's radiative balance. Since ~60% of the aerosol mass consists of complex natural and anthropogenic organic matter that absorbs in the ultraviolet and, particularly, in the visible regions of the solar spectrum, it is important to establish the chemical identity of the organic chromophores and the mechanism by which they contribute to aerosol color. Here we report studies on the chemical composition versus chromism of photolyzed (λ > 305 nm) solutions of PA, under a variety of experimental conditions that include substrate concentration, temperature and the presence of relevant spectator solutes, such ammonium sulfate. We use high resolution mass and ^1H, ^(13)C NMR spectrometries to track chemical speciation in photolyzed solutions as they go through thermochromic and photobleaching cycles. The chemical identity of the components of these mixtures does not change in these cycles, in which photobleached solutions gradually recover their yellow color in the dark with non-conventional kinetics typical of aggregation processes, we infer that visible absorptions involve the intermolecular coupling of carbonyl chromophores in supramolecular assemblies.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.gca.2009.05.006DOIArticle
http://www.sciencedirect.com/science/article/pii/S0016703709002592PublisherArticle
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0002-0432-6564
Colussi, A. J.0000-0002-3400-4101
Additional Information:© 2009 Published by Elsevier Ltd.
Record Number:CaltechAUTHORS:20151214-130754417
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20151214-130754417
Official Citation:Goldschmidt Abstracts 2009 – H, Geochimica et Cosmochimica Acta, Volume 73, Issue 13, Supplement, June 2009, Pages A484-A565, ISSN 0016-7037, http://dx.doi.org/10.1016/j.gca.2009.05.006. (http://www.sciencedirect.com/science/article/pii/S0016703709002592)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62883
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Dec 2015 21:22
Last Modified:14 Dec 2015 21:22

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