Fourier transform microwave spectrum of and Born–Oppenheimer breakdown effects in tungsten monoxide, WOThis article is part of a Special Issue on Spectroscopy at the University of New Brunswick in honour of Colan Linton and Ron Lees.Dedicated to Ronald M. Lees and Colan Linton, in recognition of their outstanding contributions to science.

Abstract

Rotational transitions of eight isotopomers of tungsten monoxide, WO, in its X0+ ground electronic state, have been measured in the frequency range 22–26 GHz, using a cavity Fourier transform microwave spectrometer. The samples were prepared by laser ablation of W metal in the presence of O2 and stabilized in pulsed supersonic jets of Ne or Ar. Only the J = 1–0 transition was accessible within the frequency range of the spectrometer. It was measured for the ground (v = 0) and two excited (v = 1, 2) vibrational states. Hyperfine structure due to 183W nuclear spin-rotation coupling was found for 183WO. The overall spectral fit used a Dunham-type expression including Born–Oppenheimer breakdown parameters. Only the v = 0 and 1 states could be fit to the measurement accuracy because of a small perturbation of the v = 2 state. It was necessary to account for the finite nuclear size of the W nucleus in the fit. The resulting parameter V 01W agreed well with a value calculated using density functional theory. Equilibrium internuclear distances re have been evaluated.