Knowledge Bank

Computations of vibration-rotation lines of the $\nu 4$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CH4$ at $1300cm-1$ have been extended to sixth order in perturbation theory. We have fit, by a least squares technique, a $0.04cm-1$ resolution laboratory spectrum obtained by Reisfeld $etal.1$ at Los Alamos. We have assigned quantum numbers for approximately 250 lines in the $1200-1400cm-1$ region. The fourth order rotational constants of Husson and $Poussigue,2$ derived from a lower resolution $spectrum,3$ were used as starting values for the parameter search. We have calculated an improved fourth order fit to the spectrum and have also obtained parameters for a sixth order fit. The line strengths adopted here are consistent with the recent work of Fox $etal.4$ Two examples of the application of this worm are given. First, a recent laser diode measurement in the $1200-1215cm-1$ region is compared to the theoretical spectrum. Second, the work is used to interpret spectra of Jupiter’s atmosphere obtained earlier this year with the infrared spectrometer on the Voyager spacecraft.