Resonant two-photon ionization spectroscopy of NiC

A spectroscopic investigation of jet-cooled diatomic NiC has revealed a complex pattern of vibronic levels in the wave number range from 21 700 to 27 000 cm(-1). Of the more than 50 vibronic bands observed, 31 have been rotationally resolved and analyzed. All are Omega'=0(+)<--Omega=0(+) transitions, consistent with the calculated (1)Sigma(+) ground state of this molecule. Through the observation of vibrational hot bands in the spectra, these measurements have established that omega(e)(')=875.155 cm(-1), omega(e)x(e)=5.38 cm(-1), B-e=0.640 38(14) cm(-1), alpha(e)=0.004 44(36) cm(-1), and r(e)=1.6273(2) Angstrom for (NiC)-Ni-58-C-12. Several possible electronic band systems are observed, but the identification of these is hampered by extensive perturbations among the excited states. The observation of long-lived vibronic states as far to the blue as 26 951 cm(-1) indicates that D-0(NiC)greater than or equal to3.34 eV, and the ionization energy of NiC has been determined to fall in the range IE(NiC)=8.73+/-0.39 eV. A discussion of these results, in the context of work on other 3d transition metal carbides is also presented. (C) 2002 American Institute of Physics.