THE SURFACE-CHEMISTRY OF CU (100) IN HCL SOLUTIONS AS A FUNCTION OF POTENTIAL - A STUDY BY LEED, AUGER-SPECTROSCOPY AND DEPTH PROFILING

The surface chemistry of Cu (100) in HCl solutions has been examined by Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and Auger depth profiling (ADP). Electrochemistry was conducted in an antechamber directly coupled to an UHV surface analysis instrument. (2 1 2 ×2 1 2R45° LEED pattern formed in HCl regardless of potential or Cl- concentration. The extent of Cl adsorption from 1 mM HCl varied only slightly with potential. Immersion of a Cl-coated electrode into 1 mM H2SO4 at a series of potentials showed more clearly the reductive desorprion of Cl at potentials negative of -0.31 V (vs. Ag/AgCl). Sulfate adsorption at negative potentials resulted in a Cu(100)(2× 2)-SO2-4 structure. Anodic polarization of the electrode in 10 mM HCl resulted in streaks in the 2 1 2 ×2 1 2R45° LEED pattern due to formation of CuCl islands on the (2 1 2×2 1 2R45° -Cl surface. CuCl island formation was verified by depth profiling. © 1990.