dc.creator Julienne, P. S. en_US dc.creator Neumann, D. en_US dc.creator Krauss, M. en_US dc.date.accessioned 2006-06-15T13:23:45Z dc.date.available 2006-06-15T13:23:45Z dc.date.issued 1971 en_US dc.identifier 1971-D-1 en_US dc.identifier.uri http://hdl.handle.net/1811/8652 dc.description Author Institution: National Bureau of Standards en_US dc.description.abstract The absorption cross section of the diffuse absorption bands of $CO_{2}$ in the region 1750-1200 \AA is of prime importance for understanding $CO_{2}$ photolysis, especially as a constituent of a planetary atmosphere. The upper state of the absorption is a $^{1}B_{2}$ state correlating with a $^{1}\Delta_{u}$ state in the linear geometry. Although the cross section for this vibronically allowed electric-dipole absorption will be temperature dependent, there are no experimental studies of this temperature dependence, and room temperature values have been used in discussions of the atmospheres of Mars and Venus despite the widely disparate temperature distributions of their atmospheres. We have calculated the temperature dependence of the integrated absorption coefficient for the 1750-1200 \AA region. The electronic energies and transition moments were calculated ab initio as a function of the bending angle of the molecule; the Renner type splitting of the degenerate $^{1}\Delta_{u}$ state into $^{1}B_{2}$ and $^{1}A_{2}$ energy curves is obtained. The integrated absorption cross section is proportional to the square of the transition moment averaged over the ground state vibrational wave functions. At room temperature the average of the transition moment squared over a Boltzmann distribution is $2.9 \times 10^{-3}$ $(ea_{{o}})^{2}$, which corresponds roughly to an oscillator strength of $6 \times 10^{-4}$. Although halving the temperature produces only about 10\% decrease in absorption, there is a dramatic increase by 75\% when the temperature is doubled. The temperature dependence of individual lines, particularly in the wings of the overall distribution, is likely to be even more sensitive. en_US dc.format.extent 183367 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title CALCULATION OF THE TEMPERATURE DEPENDENCE FOR ABSORPTION IN $CO_{2}$ IN THE 1750-1200 \AA REGION en_US dc.type article en_US
﻿