LASER SIDE BAND SPECTRUM OF THE $\nu_{2}/\nu_{4}$ DIAD OF AsH3 AND PH3; SATURATION OF PERTURBATION ALLOWED TRANSITIONS

Abstract

The $\nu_{2}/\nu_{4}$ (907/999 $cm^{-1}$) diad of the arsine molecule has been investigated between $875 cm^{-1}$ and $1086 cm^{-1}$ with tunable IR laser sidebands at an absolute accuracy of $<$150kHz and a resolution of better than 300 kHz. Eleven $A_{1}$/$A_{2}$ doublets have been resolved for the first time. Three perturbation allowed transitions could be saturated, A fit of 70 parameters achieved a standard deviation of 156 kHz. On the phosphine molecule, which exhibits a fairly weak absorption spectrum on the $\nu_{2}/\nu_{4}$ (992/1118 $cm^{-1}$) diad, 48 allowed saturated transitions could be observed, among them four k = 6 doublets. Including data from the literature an overall standard deviation of 1.2 Mhz was obtained.