HREELS INVESTIGATION OF THE ORIENTATION AND DEHYDROGENATION OF CYCLOHEXANE ON PT[111]

In this article, we report on the investigation of cyclohexane adsorbed on Pt[111] with high resolution electron energy loss spectroscopy (HREELS). Variation of the angle of incidence of the electron beam is used to determine the orientation of the adsorbed molecule. The symmetry of the adsorbate/surface complex is C3v, which indicates adsorption with the C3 axis of the molecule perpendicular to the surface, i.e., with the plane of the molecule parallel to the surface. Annealing of the surface to different temperatures followed by HREELS of the resultant species shows that dehydrogenation begins by 200 K, but that benzene is not formed until 300 K. Spectra between 200 and 300 K show very little variation, implying a single predominant intermediate. Angular profiles after annealing to 260 K indicates the intermediate/surface complex has low symmetry and lends insight to the possible identity.