VIBRATIONAL ANHARMONICITY OF SF6SF_{6} IN CRYOGENIC SOLUTION

$^{1}$ V.V. Bertsev, T.D. Kolomiitseva, and N.M. Tsyganenko, Opt. Spectrosc. 37, 263 (1974). $^{2}$ S.R.J. Brueck, to be published. Experimental work supported by the Department of the Air Force.Author Institution:The infrared spectrum of $SF_{6}$ has been recorded in liquid $oxygen^{1}$ and liquid $argon^{2}$ solutions. The suppression of rotational structure and the elimination of hot bands at low temperature give estimates of band origins that could only be achieved in the gas phase by detailed high-resolution analyses of each hand. A normal coordinate anharmonic force field has been fitted directly to fundamental, overtone and combination bands of the cryogenic solution spectra. It will be shown that at least for $\nu_{3}$ the derived anharmonic constants are in good agreement with those obtained from gas phase data (and force fields based upon gas phase data), despite appreciable shifts in the fundamentals from gas to cryogenic solution

HIGH-RESOLUTION STIMULATED RAMAN SPECTROSCOPY OF THE ν1\nu_{1} BAND OF SiH4SiH_{4}

1. A Owyoung, C. W. Patterson, and R. S. McDowell, Chem. Phys. Lett. 59, 156 (1978). 2. R. S. McDowell, C. W. Patterson, and A. Owyoung, J. Chem. Phys., in press. 3. A. Cabana, D. L. Gray, A. G. Robiette, and G. Pierre, Mo1. Phys. 36, 1503 (1978)Author Institution:A Doppler-limited isotropic Raman spectrum of the symmetric stretching fundamental $(\nu_{1})$ of $^{28}SiH_{4}$ has been recorded using high-sensitivity “quasi-cw” inverse Raman spectroscopy. Unlike the corresponding fundamentals of $^{12}CH_{4}$ (1) and $^{13}CH_{4}$ (2), this band exhibits compact non-overlapping J manifolds that extend over about $5 cm^{-1}$. Since $\nu_{1}$ and the infrared-active stretch $\nu_{3}$ reported by Cabana et al. (3) and the Raman frequencies of $\nu_{1}$ Q (0) through Q(14). The results confirm the infrared analysis (3), in which several perturbation-allowed $\nu_{1}$ transitions were identified in absorption, but the molecular constants are much better determined by the inclusion of the Raman data. Significant intensity perturbations occur at higher J due to a break down of the selection rule $\Delta=0$ (N is the index distinguishing between levels of the same J and rovibrational symmetry), and have been quantitatively accounted for

LINE ASSIGNMENTS AND INTENSITIES FOR THE ν2+ν4\nu_{2} + \nu_{4} BAND OF METHANE

Author Institution: Jet Propulsion Laboratory; Department of Physics, Florida State University; Department of Chemistry, The University, Whiteknights, ReadingThe forbidden transitions have been identified and allowed transitions assignments extended for the $\nu_{2} + \nu_{4}$ band of $CH_{4}$ using spectra recorded at $0.023\, cm^{-1}$ resolution with the four-pass grating spectrometer at Florida State University. The assignment process has been greatly aided by the measurement of individual line strengths at different temperatures to obtain experimental values for the ground state energy levels of the transitions. Corresponding allowed transitions of $\nu_{2} + \nu_{4}$ of $^{13}CH_{4}$ have been identified

INFRARED ABSORPTION LINE ASSIGNMENTS AND STRENGTHS FOR THE 2ν22\nu_{2} BAND OF METHANE

Author Institution:A $0.02 cm^{-1}$ resolution study of the absorption line strengths of methane in the 3.3 $\mu m$ region at both room and reduced temperatures reveals over 200 lines with strengths between $1 \times 10^{-2}$ and $5 \times 10^{-5} cm^{-2} atm^{-1}$ at 296 K which belong to the $2\nu_{2}$ band. Most of these lines can be assigned with the aid of combination differences, experimental values for $E^{\prime\prime}$ and a preliminary energy level calculation

The infra-red spectra of silyl fluoride and silyl fluoride-d3

Infra-red spectra have been recorded for silyl fluoride and silyl fluoride-d3 at a resolution of circa 0·3 cm-1. Rotational structure has been observed for parallel fundamentals in both molecules, and for all perpendicular fundamentals. In both SiH3F and SiD3F the A1 and E species deformation modes interact strongly via a Coriolis perturbation; this has been analysed, and the band origin of v5 for SiH3F is reassigned. A hybrid-orbital force field based on the experimental data is also reported