Energy window effect in chemisorption of C-36 on diamond (001)-(2 x 1) surface

In this paper, the collision of a C-36. with D-6h symmetry, on diamond (0 0 1)-(2 x 1) surface was investigated using molecular dynamics (MD) simulati on based on the semi-empirical Brenner potential. The incident kinetic ener gy of the C-36 ranges from 20 to 150 eV per cluster. The collision dynamics was investigated as a function of impact energy Ei,. The C,h cluster was f irst impacted towards the center of two dimers with a fixed orientation. It was found that when Ei, was lower than 30 eV, C-36 bounces off the surface without breaking up. Increasing E-in to 30-45 eV, bonds were formed betwee n C36 and surface dimer atoms, and the adsorbed C-36 retained its original free-cluster structure. Around 50-60 eV, the C-36 rebounded from the surfac e with cage defects. Above 70 eV. fragmentation both in the cluster and on the surface was observed. Our simulation supported the experimental finding s that during low-energy cluster beam deposition small fullerenes could kee p their original structure after adsorption (i.e. the memory effect), if E- in is within a certain range. Furthermore, we found that the energy thresho ld for chemisorption is sensitive to the orientation of the incident C36 an d its impact position on the asymmetric surface. (C) 2001 Elsevier Science B.V. All rights reserved.