Copper overlayers on rhenium(0001)

Abstract

The interaction of Cu overlayers with a Re(0001) surface has been studied by low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), thermal desorption spectroscopy (TDS), and electron energy loss spectroscopy (ELS). The thermal desorption spectra of Cu from Re(0001) indicate two desorption peaks, designated as {beta}{sub 1} and {beta}{sub 2} states. The {beta}{sub 1} state begins to appear upon saturation of the {beta}{sub 2} state. Both states follow approximate zero-order kinetics. The activation energy for the {beta}{sub 1} and {beta}{sub 2} states is estimated from TD spectra to be {approx} 74 and {approx} 93 kcal/mol, respectively. AES measurements show that with Cu coverages less than 2 monolayers (ML), the Cu to Re AES ratios remain constant upon annealing to 1000 K. At higher coverages of Cu, the Cu/Re AES ratios decrease when annealed between 110 and 900 K, consistent with the formation of 3-D Cu clusters. Some Cu nucleation appears to take place during the deposition at 110 K. Several surface phases are observed by LEED following Cu deposition at 110 K and subsequent annealing.