Self-assembly of C_(60) fullerenes on quasi-one-dimensional Si(111)4× 1-In surface

摘要

Using scanning tunneling microscopy observations, self-assembly of C_(60) fullerenes in the course of room-temperature adsorption onto Si(111)4×1 -In reconstruction and after subsequent annealing at temperatures ranging from 150 to 450 ℃ has been studied. Adsorbed C_(60) fullerenes have been found to occupy off-centered positions on In-atom rows forming linear chains with a maximal length of eight C_(60) molecules. Intermolecular spacing within the regular chains equals three lattice constants of Si(111) surface. Two energetically different adsorption states of C_(60) have been detected, one of which is occupied preferentially at room temperature, while occupation of the second (more tight) state dominates at temperature above -150 ℃. In the first state, C_(60) fullerene resides plausibly in a continuous rotation, while in the second state a C_(60) molecule is fixed tightly in a single orientation with a C_(60) hexagon pointing upward. Transition of C_(60) fullerenes to the more stable state is accompanied by expelling In atoms from the Si(111)4×1-In reconstruction.