An STM study of the chemisorption of C2H2 on Si(001)(2×1)

The chemisorption of ethylene (C 2 H 4 ) on Si(001)(2×1) at 300 K has been studied by scanning tunneling microscopy (STM) and spectroscopy (STS). Exposure of the surface to C 2 H 4 does not cause large scale rearrangement of the original Si surface atoms. The adsorption of individual molecules and changes in the local structure can, however, be observed. At low coverage, the C 2 H 4 molecules prefer to adsorb on alternate dimer sites creating either a local (2×2) or c(2× 4) structure. The individual domains are relatively small (<50 A) and the change in reconstruction cannot be detected by any diffraction technique