Growth and Structure of Mn Overlayers on Rh(100) Surface:A AES,UPS and LEED Study

Interfaces prepared by vapor deposition of Mn onto Rh（100） surfaces have been examined using AES,UPS and LEED.Manganese deposition was conducted respectively at 300K and 600K,and the surface composition and order were examined as a function of temperature by further annealing up to 1200K.Plots of AES uptakes（signal versus deposition time）indicated that the Mn film growth mode can be described by a layer-by-layer process only up to the first three to four adlayers at 300K,and evidence of disordered growth is inferred for higher Mn coverages.For deposition at 600K,AES data indicated significant interdiffusion and surface alloy formation.LEED observations（recorded at a substrate temperature of 300K）showed that a c（2×2）pattern appeared when Mn diffused into the Rh（100）to a certain depth.The work function of the Rh（100）c（2×2）-Mn surface alloy is smaller than that of the pure Rh （100）.Annealing experiments with various atates of Mn on Rh（100）were also measured by AES and LEED.The Mn films on Rh（100）,deopsited at 300K,were stable up to 600K,For annealing temperatures above 300K,a c（2×2）pattern was observed.Mn diffused into Rh（100）,and the ordered c（2×2）LEED pattern was again suggested to arise from the Rh-Mn surface alloy.The Mn signal decreased substantially by annealing up to 900K,and at this temperature surface alloy decomposition and Mn desorption started.For an annealing temperature up to 1200K,the Mn AES signals disappeared.