Tungsten carbide revisited: New anion photoelectron spectrum and density functional theory calculations

A new anion photoelectron (PE) spectrum of WC^- is presented and analyzed using existing and new calculations. This spectrum is different from the PE spectrum previously published [X. Li et al., J. Chem. Phys. 111, 2464 (1999)], which we suggest was actually the PE spectrum of W^-. The ground anion state is determined by calculations and comparison with spectral features to be the ²Δ^3/2 state. The ³Δ¹ - ²Δ^3/2transition is observed at an electron binding energy of 2.155 eV, which corresponds to the adiabatic electron affinity of WC. The bond length of the anion is determined to be 1.771(5) Å. A number of spectral assignments corresponding to both excited anion and neutral states are made based on previously obtained fluorescence spectra [S. M. Sickafoose et al., J. Chem. Phys. 116, 993 (2002)] and density functional theory calculations.