Near-threshold photoionization to probe neutral ''met-car'' clusters

Metal-carbon compound clusters of Ti, Zr, V, and Nb are produced by laser vaporization in a pulsed nozzle cluster source. The distribution of neutral clusters is investigated by time-of-flight mass spectrometry, with photoionization at a variety of laser wavelengths. Laser wavelength and power dependence studies are used to investigate ionization potentials of different metal-carbon clusters and the role of fragmentation in the appearance of mass distributions. The M(8)C(12) met-car clusters of zirconium, vanadium, and niobium have vertical ionization potentials greater than 5.76 eV. Ti8C12 has a vertical ionization potential of 4.9 + 0.2 eV.