Torsional splitting and l-doubling in the ν9 R Q 0 infrared band of ethane

A high resolution diode laser absorption spectrum of the ν9 R Q 0 branch of C2H6 at 822 cm-1 reveals a rotational progression with anomalous spacing and intensity, which is shown to be a result of both l-doubling and torsional splitting of rotational levels, both of which give rise to a J(J+1) energy dependence. From a contour analysis of the spectrum we estimate values for the l-doubling and torsional splitting parameters.