Coriolis intensity perturbations of the nu/sub 4/ band of SF/sub 6/
In the nu/sub 4/ band of /sup 32/SF/sub 6/ the intensity of absorption by the R branch has been found to exceed that of the P branch by 38%. This is substantially larger than the 15% excess that one calculates from ordinary rotational statistics and the nonnegligible width of the band. The authors attribute this imbalance to Coriolis interactions between the rovibrational sublevels (a) of the nu/sub 3/ and nu/sub 4/ excited vibrational states, and (b) of the ground vibrational state and the l = 1 (F/sub 1g/) level of the nu/sub 3/ + nu/sub 4/ combination state. The intensities of the observed P- and R-branch lines have a superposed Herman-Wallis type F factor of the form F(m) = (1 + xi/sub 4/m)/sup 2/, where m = -J for the P branch, 0 for the Q branch, and +(J + 1) for the R branch, and J is the rotational sublevel in the ground state. Xi/sub 4/ was determined by a new method from the relative intensities of the P, Q, and R branches. New evidence is reported that supports an earlier conclusion that the first derivatives of the dipole moment function, ..mu../sub 3/ = delta ..mu../delta q/sub 3/ and ..mu../sub 4/= delta ..mu../deltaq/sub 4/, have the same sign. The corresponding Coriolis effect is calculated for UF/sub 6/. It is predicted that Coriolis interactions induce weak absorption in the nu/sub 6/ bands of SF/sub 6/ and UF/sub 6/, which would otherwise be inactive according to selection rules for strong infrared absorption or Raman scattering. An order of magnitude estimate of the absorption intensity of the induced nu/sub 6/ band of SF/sub 6/ agrees with a recent observation of that infrared spectral region. 50 references, 4 figures, 10 tables.
- Research Organization:
- Los Alamos National Lab., NM
- OSTI ID:
- 5481091
- Journal Information:
- J. Mol. Spectrosc.; (United States), Journal Name: J. Mol. Spectrosc.; (United States) Vol. 98; ISSN JMOSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Atomic & Molecular Theory-- (-1987)
74 ATOMIC AND MOLECULAR PHYSICS
CORIOLIS FORCE
ENERGY LEVELS
EXCITED STATES
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
INFRARED SPECTRA
RAMAN EFFECT
SPECTRA
SULFUR COMPOUNDS
SULFUR FLUORIDES
VIBRATIONAL STATES