The bond length and bond energy of gaseous CrW

摘要

Supersonically cooled CrW was studied using resonant two-photon ionization spectroscopy. The vibronically resolved spectrum was recorded over the region 21 100 to 23 400 cm(-1), showing a very large number of bands. Seventeen of these bands, across three different isotopologues, were rotationally resolved and analyzed. All were found to arise from the ground (1)Sigma(+) state of the molecule and to terminate on states with Omega' = 0. The average r(0) bond length across the three isotopic forms was determined to be 1.8814(4) angstrom. A predissociation threshold was observed in this dense manifold of vibronic states at 23 127(10) cm(-1), indicating a bond dissociation energy of D-0(CrW) = 2.867(1) eV. Using the multiple bonding radius determined for atomic Cr in previous work, the multiple bonding radius for tungsten was calculated to be 1.037 angstrom. Comparisons are made between CrW and the previously investigated group 6 diatomic metals, Cr-2, CrMo, and Mo-2, and to previous computational studies of this molecule. It is also found that the accurately known bond dissociation energies of group 5/6 metal diatomics Cr-2, V-2, CrW, NbCr, VNb, Mo-2, and Nb-2 display a qualitative linear dependence on the sum of the d-orbital radial expectation values, < r >; this relationship allows the bond dissociation energies of other molecules of this type to be estimated. Published by AIP Publishing.