NEW RESULTS FROM THE ROTATIONAL SPECTRA OF THE HALOGEN MONOXIDES. INTERATOMIC POTENTIALS, FINE AND HYPERFINE INTERACTIONS.
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Date
2000
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Last year we reported to IO rotational spectrum in vibrational levels up to v = 13 for the $X_{1}{^{2}}\Pi_{3/2}$ state and to v= 9 for the $X_{2}{^{2}}\Pi_{1/2}$ state. In comparison, previous studies of BrO were limited to v = 2 for $X_{1}$ and v=1 for the $X_{2}$ state. Using the DC discharge cell that was so effective for vibrational excitation of IO, measurements of BrO have now been extended up to v=8 and v=7 for the $X_{1}$ and $X_{2}$ states, respectively. Excited vibrational levels of CIO were not obtained with these methods, however good signal to noise at thermal populations allowed measurements for the v=2 levels of both the $X_{1}$ and $X_{2}$ states as well as $^{18} O$ in natural abundance. The Hamiltonian of Brown, $et. al.^{a}$ with explicit isotope dependencies for each parameter, has provided a set of mass and nuclear moment independent parameters for each of the halogen monoxide species. The electron spin-rotation constant, $\gamma$, and the centrifugal distortion of the spin-orbit splitting, $A_{D}$ which are normally correlated, have been separately determined by the isotope dependence of their contributions to the spectrum. Interatomic potentials have been derived from the mass-independent parameters that are accurate up to the observed excitation energies for each molecule. Analyses of the fine-structure parameters indicate that these molecules are close to the single perturber limit. The hyperfine parameters will be compared with the literature $values^{b,c,d}$ of the appropriate calculated relativistic radial integrals of the halogens.
Description
$^{a}$J. M. Brown and J. K. G. Watson, J. Mol. Spec. 148, 371(1991). $^{b}$P. Pyykk\""o, M. Seth, Theor. Chem. Acc. 96, 92-104(1997) $^{c}$I. Lindgren and A. Ros\'en. Case Studies in Atomic Physics, 4, 197-298 (1974) $^{d}$P. Pyykk\""o and L. Wiesenfeld, Mol. Phys. 43, 557-580(1981).
Author Institution: Jet Propulsion Laboratory, California Institute of Technology; Department of Chemistry, Haverford College; I. Physikalisches Institut, Universit\""at zu K\""oln
Author Institution: Jet Propulsion Laboratory, California Institute of Technology; Department of Chemistry, Haverford College; I. Physikalisches Institut, Universit\""at zu K\""oln