The adsorption of S-2 on the Si(1 1 1)-(7 x 7) surface and the interaction of copper and sulfur on this sulfur-terminated Si(1 1 1) surface have been studied using synchrotron irradiation photoemission spectroscopy and scanning tunneling microscopy. The adsorption of S-2 at room temperature results in the passivation of silicon dangling bonds of Si(1 1 1)-(7 x 7) surface. Excessive sulfur forms S-n species on the surface. Copper atoms deposited at room temperature directly interact with S-adatoms through the formations of Cu-S bonds. Upon annealing the sample at 300 degrees C, CuSx nanocrystals were produced on the sulfur-terminated Si(1 1 1) surface. (C) 2010 Elsevier B.V. All rights reserved.