Delayed ionization and delayed atomic ion emission of Ti and V metallocarbohedrenes. Evidence for collective electronic effects

Investigations of the ionization of titanium and vanadium carbon clusters reveal prompt ionization for the entire range of species produced, and a significant delayed ion signal for the metallocarbohedrenes (Met-Cars), M8C12. At high laser fluences, emission of delayed atomic metal ions is also observed as a second ionization channel. Neither channel exhibits a dependence on excitation wavelength, but strong laser fluence dependencies are seen. The findings are consistent with thermionic emission from the Met-Car. Delayed atomic emission resulting from further excitation to highly excited states of Met-Cars occurs in an energy range where a giant dipole resonance has been predicted.