CU-O ATOMIC CHAINS OBSERVED ON AN ULTRATHIN-FILM OF CU(110)

The fringe contrast observed in a copper film with its Cu[110] paralle l to the incident electron beam has been investigated by high-resoluti on electron microscopy (HREM). According to a geometrical analysis for these fringes, it was assumed that they originated from the Cu-O chai ns adsorbed on a Cu(110) surface. This assumption was confirmed by a m ultislice image simulation on the basis of the electron diffraction an d imaging theory using an added-row reconstruction model. Our calculat ion indicates that an added-Cu-O-chain surface reconstruction can gene rate a regular fringe pattern with sufficient contrast in a thin coppe r film with a thickness of several nanometers. The present study demon strates the potential of HREM to investigate surface structures and su rface reaction of ultrathin films at the atomic level.