HR: 0830h
AN: A11F-0038    [PDF]
TI: Photolysis of PAN at High Latitude
AU: * Flowers, B A
EM: flowersba@mail.utexas.edu
AF: Chemistry and Biochemistry Department The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712-0165 United States
AU: Phillips, G J
EM: ffgjp@uaf.edu
AF: Department of Chemistry Geophysical Institute University of Alaska, Fairbanks, 930 Koyukuk Dr., Fairbanks, AK 99775-6160 United States
AU: Simpson, W R
EM: ffwrs@aurora.uaf.edu
AF: Department of Chemistry Geophysical Institute University of Alaska, Fairbanks, 930 Koyukuk Dr., Fairbanks, AK 99775-6160 United States
AU: Stanton, J F
EM: stanton@jfs1.cm.utexas.edu
AF: Chemistry and Biochemistry Department The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712-0165 United States
AB: Tropospheric composition is in part determined by chemical reactions between anthropogenic and biogenic compounds. Acetyl peroxynitrate (PAN) is formed from reactions of partially oxidized hydrocarbons and NO$_{\rm x}$. Once formed, PAN can remain stable thereby transporting quantities of NO$_{\rm x}$ from regions of high hydrocarbon-NO$_{\rm x}$ pollution to remote areas of the globe. In Arctic regions, the thermal decomposition of PAN is slowed to a rate comparable to that of UV photolysis. The primary photoproducts from PAN are NO$_2$ and NO$_3$. Photolysis producing NO$_2$ and acetyl peroxy radical is reversible with their recombination to form PAN. Photolytic decomposition to NO$_3$ and acetate radical is not reversible,thus leading to irreversible PAN loss. We report measurements of the quantum yield of NO$_3$ from PAN photolysis. By detecting nitrate radical using cavity ring-down absorption spectroscopy, a highly precise value of $\phi_{\rm NO_3}$ = 0.30 $\pm$ 0.06 is determined. Previous modeling studies of PAN photolysis results have assumed wavelength independence. The results presented indicate the possibility of a wavelength dependence of $\phi_{\rm NO_3}$. Atmospheric implications of PAN photolysis in the Arctic will be discussed.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0317 Chemical kinetic and photochemical properties
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting