The nu(1)=1 and nu(3)=1 states of AsF3 studied by high resolution IR and millimeterwave spectroscopy: the equilibrium structure of AsF3

The high resolution (0.0025 cm(-1)) infrared spectrum of AsF3 in the nu(1) (nu(0) 740.5708 cm(-1)) and nu(3) region (nu(0) 702.5650 cm(-1)) was record ed and rotationally analyzed. Millimeterwave transitions within the nu(1) = 1 and nu(3) = 1 states were measured in the 340-470 GHz region. Owing to t he observation of numerous perturbation-allowed transitions in the nu(3) ba nd, which are caused by r resonance effects occurring for different K value s, C-0, D-K(0) and H-K(0) have been determined. All experimental observatio ns on nu(1) and nu(3) have been fitted together employing two different and equivalent reductions of the rovibrational Hamiltonian, one constraining q (3) and the other one B Omega zeta(13)(y), to zero. A significantly improve d r(e) structure of AsF3 has been determined, r(e)(AsF) 1.7043(2) Angstrom and alpha(e)(FAsF) 95.88(4)degrees. (C) 2000 Elsevier Science B.V. All righ ts reserved.