Dealyed Ionization of and Delayed Atomic Emission from Metallocarbohedrenes

摘要

An investigation of titanium-carbon and vanadium-carbon clusters shows prompt photoionization for the entire distribution of species produces in the laser vaporiation plasma reactor. Both the titanium and vanadium containng metallocarbohedrenes, (Met-Cars), display significant delayed ionization behavior which is not evident for the other stoichiometries present in the cluster distribution. Also, at high excitation laser fluences, emission of atomic metal ions is observed as a second delayed ionization channel. Neither of these delayed channels exhibits a dependence on excitation wavelength, but a strong dependence on the laser fluence is seen. these findings are discussed in terms of thermionic emission from the Met-Car clusters, with the delayed atomic metal ion emission resulting from further excitation to highly excited states of the metallocarbohedrenes. These excitations fall in the energy range of a recently predicted giant dipole resonance for the metallocarbohedrenes.