Heavy atom nitroxyl radicals. IV. Experimental and theoretical studies of the F(2)P=S free radical in the gas phase.

The difluorothiophosphoryl (F(2)PS) free radical has been produced in a supersonic discharge jet from a precursor mixture of F(3)PS and high pressure argon and detected by laser-induced fluorescence and single vibronic level emission spectroscopy. With the aid of high level ab initio predictions of the properties of the ground and first two excited doublet states, the observed band system has been positively identified as B(2)A(')-X(2)A('). The electronic transition involves promotion of an electron from the pi to the pi( *) orbital with concomitant increases in the out-of-plane angle and PS bond length on excitation. The observed vibrational structure, Franck-Condon profile, rotational band contours, T(0) energy, and ground and excited state vibrational frequencies are all in accord with expectations based on our theoretical predictions.