Near-IR photodissociation of peroxy acetyl nitrate S. A. Nizkorodov1, J. D. Crounse2, J. L. Fry2, C. M. Roehl3, and P. O. Wennberg3 1Department of Chemistry, University of California at Irvine, Irvine, CA 92697, USA 2Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA 3Division of Geological and Planetary Sciences and Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, 91125, USA
Abstract. Measurements of the C-H overtone transition strengths combined with
estimates of the photodissociation cross sections for these transitions
suggest that near-IR photodissociation of peroxy acetyl nitrate (PAN) is
less significant (Jnear-IR≈3x10-8s-1 at
noon) in the lower atmosphere than competing sinks resulting from
unimolecular decomposition and ultraviolet photolysis. This is in contrast
to the photochemical behavior of a related peroxy nitrate, pernitric acid
(PNA), that undergoes rapid near-IR photolysis in the atmosphere with
Jnear-IR≈10-5s-1 at noon (Roehl et al., 2002). This difference is attributed to the larger
binding energy and larger number of vibrational degrees of freedom in PAN,
which make 4νCH the lowest overtone excitation with a high
photodissociation yield (as opposed to 2νOH in PNA).
Citation: Nizkorodov, S. A., Crounse, J. D., Fry, J. L., Roehl, C. M., and Wennberg, P. O.: Near-IR photodissociation of peroxy acetyl nitrate, Atmos. Chem. Phys., 5, 385-392, doi:10.5194/acp-5-385-2005, 2005.