ORDERING OF COPPER SINGLE-CRYSTAL SURFACES IN SOLUTION - CONFIRMATION BY LOW-ENERGY ELECTRON-DIFFRACTION

In situ restoration of crystalline order has been achieved on Cu(100) electrodes purposefully disordered by oxidation or ion bombardment. An ordered surface has also been produced on a fresh, mechanically polished Cu(100) electrode, without ion bombardment or annealing. Ordering in the above cases was achieved by chemical and electrochemical etching in an instrument which combines ultrahigh vacuum (UHV) surface analytical techniques with an antechamber for running electrochemical experiments. Verification of surface order was performed by low-energy electron diffraction (LEED), scanning electron microscopy (SEM), and scanning tunneling microscopy (STM), whereas surface elemental analysis was performed by Auger electron spectroscopy (AES). A (√2 × √2) R45° LEED pattern was obtained when Cu(100) crystals, whose surfaces had been disordered by ion bombardment or oxidation, were immersed in 1 mM HC1. The same pattern was obtained when a freshly polished Cu(100) surface was immersed in concentrated etch solution (4M H2SO4, 2M HNO3, 10 mM HCl), although this surface showed a lower degree of order. An indication of the morphology necessary to produce LEED patterns was provided by STM and SEM. © 1990, The Electrochemical Society, Inc. All rights reserved.