TOLUENE ADSORPTION ON NI(111)

The adsorption Of toluene on Ni(111) at 110 K has been studied by reflection absorption infrared spectroscopy (RAIRS). These data show that the presence of the methyl grouP significantly disrupts the pi-interaction of the aromatic ring with the substrate, leading to a weakly adsorbed molecule in which only the CH3 group is significantly perturbed by the presence of the metal surface. Toluene is initially adsorbed with its aromatic ring parallel to the surface. Increased coverage in the first layer leads to slight tilting of the aromatic ring towards both the x-z and y-z planes, where z is defined as the surface normal. This molecular geometry persists in the multilayers when adsorption is carried out at 110 K. However, annealing the multilayers leads to a reorientation of the molecules whereby the aromatic ring preferentially tilts away from the surface about the axis perpendicular to the Ph-Me bond.