THE INTERACTION OF ETHYLENE, ACETYLENE AND BUTADIENE WITH A CLEAN TUNGSTEN-(100) SURFACE

The interactions of ethylene, acetylene and butadiene with a W(100) su rface at 300 K have been investigated using photo electron spectroscop y, work function measurement and thermal desorption techniques. The co urse of the interaction is shown to be coverage dependant. At low cove rage, acetylene is initially decomposed on the surface to its constitu ent atoms carbon and hydrogen, followed by the formation of a molecula r species (I) as the coverage is increased. Further exposure results i n the displacement of adsorbed hydrogen atoms by (I) and then the form ation of a second adsorbed species (II) at the expense of (I). At satu ration, all four species are present to some extent. With butadiene, a ll three adsorption regimes are again observed, but with ethylene only the first two are apparent. The nature and bonding of the adsorbed sp ecies (I and II) are discussed. (C) 1998 Elsevier Science B.V.