Optical spectroscopy of tungsten carbide (WC)
Abstract
Resonant two-photon ionization spectroscopy has been used to study the diatomic transition-metal carbide, WC. A low-resolution scan revealed a five-member vibrational progression beginning with the 0-0 band at 17 585 cm-1. Analysis of this progression yielded a vibrational frequency of ωe'(184W12C)=752.6(4.9) cm-1 and a bond length of re'(184W12C)=1.747(4) Å. Several unassigned bands were also rotationally resolved and analyzed. All of the observed bands are Ω'=2←Ω″=1 transitions, confirming the predicted ground state of 3Δ1 arising from a 14σ28π415σ24δ116σ1 configuration. The measured line positions in these bands were simultaneously fitted to provide B0″=0.509 66(10) cm-1 for 184W12C, corresponding to r0″(184W12C)=1.713 5(2) Å. These values are corrected for spin-uncoupling effects in the ground state and represent our best estimate of the true bond length of WC. Dispersed fluorescence studies provide the ground-state vibrational constants of ωe=983(4) cm-1 and ωexe=11(1) cm-1, and have also permitted the low-lying [1.2] 3Δ2 and [4.75] states to be located and characterized. These results on WC are discussed in relation to the isovalent molecule MoC and other transition-metal carbides.
- Publication:
-
Journal of Chemical Physics
- Pub Date:
- January 2002
- DOI:
- 10.1063/1.1427068
- Bibcode:
- 2002JChPh.116..993S
- Keywords:
-
- 33.80.Eh;
- 33.80.-b;
- 33.20.Kf;
- 33.15.Mt;
- 33.15.Dj;
- 33.20.Tp;
- 33.50.Dq;
- Autoionization photoionization and photodetachment;
- Photon interactions with molecules;
- Visible spectra;
- Rotation vibration and vibration-rotation constants;
- Interatomic distances and angles;
- Vibrational analysis;
- Fluorescence and phosphorescence spectra