Molecular dynamics study of cluster deposition in thermal plasma flash evaporation

We simulated the rearrangement process of a high-temperature cluster put on a low-temperature substrate using molecular dynamics to verify the rearran gement behavior of the hot clusters. In the first step, a monoatomic homoge neous system wets simulated. A spherical fee stacked cluster consisting of 418 atoms corresponding to a 2 nm cluster, was placed on the 6 planes of a fee ( 1 1 1) substrate. The interaction potential was assumed to be the Mor se function corresponding to a material with a melting point of 1680 K. The substrate temperature T-sub and the initial cluster temperature T-cluster( init) were varied from 300 to 1000 K and from 1450 to 3000 K, respectively. In the case of T-cluster(init) < 2100 K, the degree of cluster rearrangeme nt is slight. Even at T-sub = 1000 K, the final structure was a six atomic- layer-high cap-like structure. On the other hand, clusters with T-cluster(i nit) > 2400 K rearranged markedly into almost two-dimensional clusters even at T-sub = 300 It and the degree of rearrangement seemed to be independent of the substrate temperature. It was revealed that high temperature nanosc ale clusters could deform easily even on a room-temperature substrate owing to their high internal energy. This was confirmed by scanning tunneling mi croscopy, (C) 1999 Published by Elsevier Science Ltd. All rights reserved.