Torsional splitting andl-doubling in the ν₉^RQ₀infrared band of ethane

Torsional Splittings in the Band ν9+ ν4− ν4of Ethane

“…These splittings increase rapidly with increasing torsional quantum number, , as the torsional energy increases toward the barrier height. As a result of the high degree of symmetry of the molecule, the torsional motion 4 separates completely from vibration and rotation to first order, and torsional splittings in a given vibrational state are independent, to first order, of rotational quantum number but depend only on the torsional quantum number and the barrier to internal rotation in that vibrational state (1).…”

“…Patterson et al (4) indirectly observed the effects of torsional splittings in the diode laser spectrum of the R Q 0 band of 9 , primarily in the form of an intensity perturbation. From a contour analysis, Patterson et al determined that the splittings in K ϭ 0 were dependent on J in the form S 0 ( J) ϭ S 0 ϩ F 0 J( J ϩ 1).…”

“…From a contour analysis, Patterson et al determined that the splittings in K ϭ 0 were dependent on J in the form S 0 ( J) ϭ S 0 ϩ F 0 J( J ϩ 1). The J dependence of the splittings was conjectured to arise from Coriolis interaction of 9 with the nearby excited torsional state 3 4 .…”

“…The theoretical formalism of Susskind et al (5) can be used to predict the splitting patterns in any band of ethane to the extent that xy Coriolis interaction involving 4 is the only source of interaction which has a different effect on the energy levels of the two torsional components involved in the transitions. In this work, we have measured and analyzed the torsional splittings in the hot band 9 ϩ 4 Ϫ 4 .…”

Torsional Splittings and Assignments of the Doppler-Limited Spectrum of Ethane in the C-H Stretching Region

“…The torsional doublets of the RR 2 (7) and RR 3 (4) lines and the interleaved RQ 5 subbranch are unambiguously characterized by their nuclear spin statistical weight intensity ratios calculated by Wilson 19]. The first observation of torsional splitting in ethane was made in diode laser spectra of the v 9 band by Patterson, Flicker, McDowell and Nereson [10]. These splittings also arise from perturbations, induced by a resonance with 3v 4 ; but since that is the only possible 238 resonance with v 9 , that band is more amenable to analysis than the complex C-H stretching bands.…”