title: Cage structure formation of singly doped aluminum cluster cations Al(n)TM+ (TM = Ti, V, Cr).
abstract: Structural information on free transition metal doped aluminum clusters, Al(n)TM(+) (TM = Ti, V, Cr), was obtained by studying their ability for argon physisorption. Systematic size (n = 5-35) and temperature (T = 145-300 K) dependent investigations reveal that bare Al(n)(+) clusters are inert toward argon, while Al(n)TM(+) clusters attach one argon atom up to a critical cluster size. This size is interpreted as the geometrical transition from surface-located dopant atoms to endohedrally doped aluminum clusters with the transition metal atom residing in an aluminum cage. The critical size, n(crit), is found to be surprisingly large, namely n(crit) = 16 and n(crit) = 19-21 for TM = V, Cr, and TM = Ti, respectively. Experimental cluster-argon bond dissociation energies have been derived as function of cluster size from equilibrium mass spectra and are in the 0.1-0.3 eV range.
authors.affiliation: Laboratory of Solid State Physics and Magnetism, Katholieke Universiteit Leuven, B-3001, Leuven, Belgium.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Lang
authors.forename: Pieterjan
authors.initials: P
authors.lastname: Claes
authors.forename: Sven
authors.initials: S
authors.lastname: Neukermans
authors.forename: Ewald
authors.initials: E
authors.lastname: Janssens