Vibrational Spectroscopy of Gas-Phase Metal-Carbide Clusters and Nanocrystals

Neutral $\mathrm{Ti}{}_8\mathrm{C}{}_{12}$ and $\mathrm{Ti}{}_{14}\mathrm{C}{}_{13}$ clusters are produced in the gas phase with pulsed-nozzle laser vaporization. Infrared multiphoton excitation with a pulsed free-electron laser results in thermionic electron emission for these clusters, and the parent molecular ions are detected. Multiphoton ionization is strongly enhanced on vibrational resonances of these clusters, making it possible to observe infrared resonance-enhanced multiphoton ionization spectra. These spectra indicate C-C bonding for the “met-cars” while $\mathrm{Ti}{}_{14}\mathrm{C}{}_{13}$ has remarkable similarities to bulk TiC.