Ordering at Cu sub 3Au(110) Surface

We have extended earlier low energy ion scattering (LEIS) and low energy electron diffraction (LEED) measurements on Cu sub 3 Au(100) sup 1,2 to Cu sub 3 AU(110). LEIS indicates fcc structure and layer compositions Cu sub 100-x Au sub x with x=43+-3 (1st), 20+-5 (2nd layer) for crystal temperatures T below the bulk disordering transition near 663K. x (1st layer) decreases significantly for T > 663K. LEED indicates a first- order 2X1->1X1 disordering transition at 663K. The ordering kinetics for fixed T-values between 590K and 640K obey a scaling relation sup 3 with d=1.1 +-0.1, and q sub 1 alpha t sup -a with a = 0.26 +- 0.03 (d - dimensionality, q sub 1 = (1/2,0) beam width, t = time). LEED also indicates 4X1 and incommensurate "hex" reconstructions.