Electron-induced "localized atomic reaction" (LAR): Chlorobenzene adsorbedon Si(111) 7x7

Electron-induced reaction of chlorobenzene (ClPh) adsorbed on silicon [Si(1 11)7x7] is shown by scanning tunneling microscopy (STM) to result in "local ized atomic reaction" (LAR), imprinting Cl as chemically-bound Cl-Si on the surface. Voltage pulses of -4 V from the STM tip give LAR restricted to th e site of electron impact. Delocalized electron impact imprints the self-as sembled pattern of ClPh(ad) on the surface as Cl-Si. The imprint is found t o be on the same area of the unit cell as ClPh(ad), but at adjacent atomic sites. The occurrence of LAR is ascribed to a concerted reaction; this can only occur if the new bond (Cl-Si) is directly adjacent to the old one (Cl- Ph). (C) 1999 American Institute of Physics. [S0021-9606(99)01746-8].