THE SPECTRUM OF $HgCl_{2}$ IN THE VACUUM ULTRAVIOLET $REGION^{*}$
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Date
1963
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Ohio State University
Abstract
“The intensities of the absorotion bands in the 1700 {\AA} system of $HgCl_{2}$ were determined from photomultiplier recordings. Wavelength measurements of the sharp violet edges were obtained from photographs at a dispersion of 4.2 {\AA}/mm. The hydrogen continuum was used as background with the photomultiplier and the xenon continuum was used for the. An analysis of the system gives the following vibrational constants: The $\nu’’_{3}$ value was obtained from infrared $data^{1}$. Ten bands were used in determining these stants. The positions of sixteen other bands were calculated and their average difference from the measured positions is $5.5\;cm^{-1}$. Since $\nu_{3}’$ is smaller than $\nu_{1}’$ it appears that the potential function for the antisymmetric stretching mode is not harmonic it may be a double minimum with a small barrier. In contrast to the interpretation of $Wehrli^{2}$ and Sponer aid $Teller^{3}$, no hands have been assigned to the bending frequency, $\nu_{2}$. Using two bands, a Franck-Condon calculation gives an equilibrium Hg-Cl bond length change of 0.039 - 0.003 {\AA} between the ground and the excited state. Since the bands degrade to the red and since $\nu_{1}’$ is smaller than $\nu_{1}’’$, the bond length must be greater in the excited state. Franck-Condon calculations give intensities for all other bands which are in good agreement with observed. A second system of seven diffuse bands has also been observed near 1500 {\AA}.”
Description
$^{1}$W. Klemperer and L. Lindeman, J. Chem. Phys. 25. 397 (1956) $^{2}$M. Wehrli, Helv. Phys. Acta 13, 153 (1940) $^{3}$H. Sponer and E. Teller, Rev. Mod. Phys. 13, 75 (1941). $^{*}$Supported by the U. S. Air Force Office of Scientific Research.
Author Institution: A. and M. College of Texas
Author Institution: A. and M. College of Texas