Absolute intensities for third and fourth overtone absorptions in HNO{sub 3} and H{sub 2}O{sub 2} measured by cavity ring down spectroscopy
Photodissociation of nitric acid and hydrogen peroxide via high-lying O-H overtone absorptions in the visible may act as a source of OH radicals in the atmosphere. The authors have used cavity ring down spectroscopy to measure the absorption cross sections for the third (4{nu}{sub OH}) and fourth (5{nu}{sub OH}) overtone transitions in these molecules. The integrated cross sections are (2.25 {+-} 0.15) x 10{sup {minus}21} and (2.57 {+-} 0.24) x 10{sup {minus}22} cm{sup 2} molecule{sup {minus}1} cm{sup {minus}1} for 4{nu}{sub OH} and 5{nu}{sub OH} in nitric acid, respectively, and (4.58 {+-} 0.39) x 10{sup {minus}21} and (5.67 {+-} 0.52) x 10{sup {minus}22} cm{sup 2} molecule{sup {minus}1} cm{sup {minus}1} for 4{nu}{sub OH} and 5{nu}{sub OH} in hydrogen peroxide. For both molecules, their report is the first direct intensity measurement for 5{nu}{sub OH}, the lowest dissociative overtone transition. The authors compare their values for the lower overtones to those from previous studies, where available. Measured cross sections suggest that the contribution of direct overtone excitation to the atmospheric photodissociation of HNO{sub 3} and H{sub 2}O{sub 2} is small but not completely negligible.
- Research Organization:
- National Oceanic and Atmospheric Administration, Boulder, CO (US)
- OSTI ID:
- 20075886
- Journal Information:
- Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Vol. 104, Issue 21; Other Information: PBD: 1 Jun 2000; ISSN 1089-5639
- Country of Publication:
- United States
- Language:
- English
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