ADSORPTION OF PI-BONDED ETHYLENE AND ETHYNYL ON PD(110) - AN STM STUDY

Adsorbed states of pi-bonded ethylene at 250 K and ethynyl at 300 K on a Pd(110) surface have been studied by scanning tunneling microscopy (STM). Adsorbed pi-bonded ethylene occupies an on-top site of the Pd a tom. On the other hand, ethynyl exhibits a pair of depressed spots at both sides, located in the neighbor Pd rows, with a protrusive part be tween them. At low coverage, pi-bonded ethylene molecules form a one-d imensional (3 x 1) structure, which reflects the anisotropic intermole cular interactions, while ethynyl species do not form an ordered struc ture. (C) 1998 Elsevier Science B.V.