The preparation and characterization of rhenium modified Pt(111) and Pt(100), and platinum modified Re(0001) single crystal surfaces

Abstract

Rhenium metal grows epitaxially on Pt(111) and Pt(100) in a layer by layer mode as shown by Auger electron spectroscopy and low energy electron diffraction. The growth mode of platinum metal on Re(0001) was also found to be layer by layer. Rhenium evaporated onto Pt(111) grows with a hexagonal close-packed structure exposing the (0001) face while on Pt(100) it grows with a face centered cubic structure exposing the (100) face. The surface composition of the bimetallic Re-Pt surface can be determined from the Auger spectrum when the coverage of rhenium is less than three monolayers. Following rhenium deposition on platinum, chemical shifts were detected in the 4f levels of both adsorbate and substrate using XPS, and this is indicative of the formation of a surface alloy between the two metals. Annealing the bimetallic surface to 1150 K caused further shifts to higher binding energies for both the platinum and the rhenium 4f lines. The presence of platinum on a partially oxidized Re(0001) surface was found to catalyze the decomposition of rhenium oxides under UHV and at a temperature as low as 400° C.