title: Melting, premelting, and structural transitions in size-selected aluminum clusters with around 55 atoms.
abstract: Heat capacities have been determined for unsupported aluminum clusters, Al49(+) - Al63(+), from 150 to 1050 K. Peaks in the heat capacities due to melting occur between 450 and 650 K (well below the bulk melting point of 933 K). The peaks for Al+51 and Al+52 are bimodal, suggesting the presence of a premelting transition where the surface of the clusters melts around 100 K before the core. For clusters with n > 55 the melting temperatures suddenly drop, and there is a dip in the heat capacities due to a transition between two solid forms before the clusters melt.
authors.affiliation: Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47404, USA.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Breaux
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Neal
authors.forename: Baopeng
authors.initials: B
authors.lastname: Cao
authors.forename: Martin F
authors.initials: MF
authors.lastname: Jarrold