AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP27
Scanning Tunneling Microscopy Studies of a Cu@sub 3@Pt(111) Surface and Its Dependence on Preparation Conditions

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Surface Science Poster Session
Presenter: A.V. Teplyakov, University of Delaware
Authors: K.T. Rim, Columbia University
T. Müller, Columbia University
G.W. Flynn, Columbia University
A.V. Teplyakov, University of Delaware
Correspondent: Click to Email
A single crystal Cu@sub 3@Pt (111) sample was studied using Scanning Tunneling Microscopy (STM) and Low Energy Electron Diffraction (LEED). The preparation conditions in ultrahigh vacuum have been analyzed by varying annealing temperatures following Ar@super +@sputtering on the alloy surface. The STM study reveals that, despite a sharp 1x1 LEED pattern at three different annealing temperatures (825, 845, and 855K), the alloy surface changes from very corrugated to atomically flat over a relatively narrow temperature range. When the sample is annealed at 845K following Ar@super +@ sputtering, 10-20nm wide terraces are formed and an ordered 2x2 phase is observed. The atomically resolved STM image of the ordered 2x2 surface shows that bright protrusions correspond to Pt atoms surrounded by Cu atoms that appear dark. This ordered 2x2 phase covers approximately 10 - 15% of the surface, and a chemically mixed, disordered 1x1 phase covers approximately 85 - 90% of the surface. The 2x2 ordered phase also exhibits some defects and antiphase boundaries. Along the step edges of terraces, Pt atoms alternate with Cu atoms, and very few Pt-Pt pairs are observed on the terraces. The chemical reactivity of these two distinct surface phases with respect to HCl and 1-hexene will also be described.