Knowledge Bank

Using conventional infrared spectrometers, no fine structure is discernible in the $v3$ band of $SF6$ at $940cm-1$, even at the highest resolution. This makes a problem such as assigning the rotational levels of this molecule which are pumped by $CO2$ laser radiation an exceedingly difficult one. The recent $development1-3$ of the $Pb0,88$ $Sn0-12Te$ laser, which emits radiation in the $940cm-1$ range, is tunable quasi-continuously over a $40cm-1$ range in 1-$2cm-1$ bands, and has an intrinsic linewidth of the order of $2\times 10-6$ $cm-1$, promises to enable a complete analysis of this band to be carried out. Portions of this band have been examined with the diode laser, and an exceedingly rich fine structure observed. These spectra will be shown and correlated with band contour calculations and estimates of second-order Coriolis splitting effects.