Date of Award

1-1-2009

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Environmental Health Sciences

Content Description

1 online resource (xix, 162 pages) : illustrations.

Dissertation/Thesis Chair

Lei Zhu

Committee Members

Liang T Chu, Vincent A Dutkiewicz, James J Schwab, Oliver V Rattigan, John D Paccione

Keywords

Aldehyde Photolysis, Atmospheric Photochemistry, Cavity Ring-Down Spectroscopy, Gas and Surface Photolysis, Photochemical smog, Cavity-ringdown spectroscopy, Photochemistry

Subject Categories

Environmental Sciences

Abstract

Photochemical smog is a phenomenon associated with pollution in urban atmospheres arising from the photochemical oxidation of volatile organic compounds (VOCs) in the presence of nitrogen oxides. The oxidation process can lead to ozone and secondary air pollutants including particle formation which reduce visibility. The term "photochemical smog" is used to describe this pollutant mixture. The further degradation of secondary air pollutants could also have an impact on the atmospheric oxidation capacity. However, the atmospheric degradation mechanisms of the secondary pollutants are still not fully understood. In this dissertation, cavity ring-down spectroscopy combined with laser photolysis and Fourier transform infrared spectroscopy have been employed to investigate gas-phase photolysis of unsaturated dicarbonyls and aromatic aldehydes, and surface photolysis of acetaldehyde. The unsaturated dicarbonyls studied included trans/cis-4-oxo-2-pentenal and E,E-2,4-hexadienedial, which have been observed as ring-openning products from the OH radical initiated atmospheric photo-oxidation of aromatic hydrocarbons (AHCs). The aromatic aldehydes studied included benzaldehyde and 2-nitrobenzaldehyde, which have previously been observed as ring-retaining products from atmospheric degradation of aromatic hydrocarbons.

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