# PRESSURE AND TEMPERATURE DEPENDENCE OF THE NEAR UV ABSORPTION CROSS SECTION OF $HNO_{3}$

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 Title: PRESSURE AND TEMPERATURE DEPENDENCE OF THE NEAR UV ABSORPTION CROSS SECTION OF $HNO_{3}$ Creators: Phillips, J. A.; Vaida, V. Issue Date: 1997 Publisher: Ohio State University Abstract: In the atmosphere, $HNO_{3}$ is an important reservoir species for the odd nitrogen $(NO_{x})$ and odd hydrogen $(HO_{z})$ families, both of which contribute to the destruction of stratospheric ozone. In the sunlit atmosphere, $NO_{2}$ and OH are liberated by photolysis of $HNO_{3}$. Therefore, in order to model the distribution of these species, accurate values for the photodissociation cross section of $HNO_{3}$ are necessary, particularly for wavelengths beyond 290 nm, which dominate the available light in the lower stratosphere. Previous $investigations^{h}$ show significant discrepancies at wavelengths greater than 310 nm, and have also noted a marked temperature dependence in this region. In an effort to resolve these discrepancies, and determine if clusters of $HNO_{3}$ are affecting the previous measurements, we have reexamined the near UV absorbance cross section from 240 to 350 nm at a wide range of pressures and temperatures. Implications of these results for the observed diurnal variation of [OH] in the lower stratosphere will be discussed. Description: $^{h}$J.B. Burkholder, R.K. Talukdar, A.R. Ravishankara, and S. Solomon, J. Geophys. Res. 98, 22937, (1993); O. Rattigan, E.R. Lutman, R. L. Jones, and R.A. Cox, Ber. Bunsenges. Phys. Chem. 96, 399, (1992) and references therein. Author Institution: UCAR/NOAA Postdoctoral Research Fellow in Climate and Global Change, Department of Chemistry and Biochemistry, University of Colorado; Department of Chemistry and Biochemistry, University of Colorado URI: http://hdl.handle.net/1811/13928 Other Identifiers: 1997-RC-11