COMPOSITION AND STRUCTURE OF CU3PT(001) - A (1X1) CU TERMINATION WITHC(2X2) UNDERLAYER ORDERING

The composition and structure of the (001) oriented surface of the ord ered alloy Cu,Pt were investigated by low-energy Li+ and He+ ion scatt ering, and low-energy electron diffraction. The clean and well-anneale d surface exhibited a c(2 x 2) LEED pattern. We present evidence that the c(2 x 2) structure corresponds to an ordered c(2 x 2) Cu-Pt second layer below a (1 x 1) Cu termination. Using Li+ ions, from analysis o f the Cu and Pt critical shadowing edges, the first interlayer spacing was determined to be contracted by about 3%. The results are discusse d on the basis of surface segregation and ordering effects. (C) 1998 E lsevier Science B.V. All rights reserved.