AB-INITIO STUDY AND MILLIMETER-WAVE SPECTROSCOPY OF P2O

The millimeter-wave spectrum of P2O produced by reacting P-4 vapor wit h atomic or molecular oxygen directly inside the absorption cell has b een observed in 13 vibrational states. Reliable identification of the various vibrationally excited states has been achieved with the help o f high-level ab initio calculations resulting in accurate geometric da ta and an anharmonic force field. Careful analysis of the vibrational levels observed resulted in 13 sets of rotational and centrifugal dist ortion parameters, which have been used, in turn, to determine the equ ilibrium rotational, quartic centrifugal distortion, and rovibrational interaction constants of P2O. The 2 nu(1)-nu(3) Fermi resonance has b een analyzed. (C) 1997 American Institute of Physics. [S0021-9606(97)0 1137-9].