The delayed ionization and atomic ion emission of binary metal metallocarbohedrenes Ti(x)M(y)C(12) (M=Zr,Nb; O<=y<=4; x+y=8)

Investigations of the photophysical character of binary metal containing metallocarbohedrene clusters (Met-Cars), reveal the phenomena of delayed ionization. Additionally, the onset of a channel corresponding to delayed atomic ion emission is observed at high laser fluence, becoming progressively more significant as the fluence is raised. The fluence dependence of both the delayed electron and delayed atomic ion emission channels at 355 and 532 nm are reported, and the Met-Car delayed ion yield estimated. At moderate fluences, the yield of the delayed electron emission channel leading to the Met-Car ion is found to be on the order of 70% of the total Met-Car signal. All of the experimental findings point to thermionic emission being the operative mechanism for the delayed ionization, while the delayed atomic ion emission is evidently a new mechanism [B. D. May, S. F. Cartier, and A. W. Castleman, Jr., Chem. Phys. Lett. 242, 265 (1995)] which may be due to the collective electronic excitation of these cluster materials. (C) 1996 American Institute of Physics.