Near-IR photodissociation of peroxy acetyl nitrate

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≈3 × 10-8 s-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≈10-5 s-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 4vCH the lowest overtone excitation with a high photodissociation yield (as opposed to 2vOH in PNA). European Geosciences Union © 2005 Author(s). This work is licensed under a Creative Commons License.