Temperature dependent reaction of propene on Ni(100) single crystal surfaces

The reaction behaviour of propene on Ni(100) single crystals was studied by photoelectron spectroscopy (XPS), thermal desorption spectroscopy (TDS) an d low energy electron diffraction (LEED). Propene is molecularly adsorbed a t temperatures below 150 K. For the saturated layer, 80% of the adsorbed pr opene decomposes upon heating, as indicated by hydrogen desorption; only 20 % desorbs molecularly with desorption peaks at 160 and 225 K. No other deso rbing species can be observed. After complete dehydrogenation of propene at 500 K the remaining carbon species form a p4g-(2 x 2)C structure. The corr esponding XP spectra show two distinct Cls peaks, probably due to carbon sp ecies located in different adsorption sites. Further increase of the temper ature of the Ni(100) crystal to 610 K results in a small shift of the bindi ng energies but without any changes in the LEED pattern. (C) 1999 Elsevier Science B.V. All rights reserved.