title: Red-Light Initiated Decomposition of α-Hydroxy Methylperoxy Radical in the Presence of Organic and Inorganic Acids: Implications for the HOx Formation in the Lower Stratosphere.
abstract: Theoretical calculations have been carried out to investigate the gas-phase decomposition of α-hydroxy methylperoxy (HOCH2(OO)) radical in the absence and presence of formic acid, acetic acid, nitric acid, and sulfuric acid. The HOCH2(OO) radical decomposition represents a new source of the HOx radical in troposphere. The results suggest that sulfuric acid will be more effective than other acids in catalyzing the peroxy radical decomposition. However, the significant stability of prereaction and postreaction complexes in all the bimolecular reactions implies a new photomechanism for the acid-mediated decomposition of the HOCH2(OO) radical that involves the visible or near IR overtone excitation of the OH stretching modes or electronic excitation of the O-O peroxy moiety in the acid-bound radical. This new overtone or electronic excitation-based photomechanism for the peroxy radical decomposition may provide useful insight into the missing photolytic source of the HOx at high solar zenith angles corresponding to the dawn or dusk photochemistry.
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln , 639 North 12th Street, Lincoln, Nebraska 68588, United States.
authors.forename: Manoj
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln , 639 North 12th Street, Lincoln, Nebraska 68588, United States.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Francisco