DETERMINATION OF AZIMUTHAL ORIENTATION WITH IMPACT SCATTERING - BITHIOPHENE ON NI(110)P(4 X 1)-S

The p(4 x 1)-S reconstructed Ni(110) surface provides a highly corruga ted template for the orientation of molecular adsorbates. Off-specular HREELS clearly shows the preferential azimuthal orientation of the bi thiophene molecule on this substrate. However, it is argued that the o rientation implied by the application of the impact scattering selecti on rule in the direction perpendicular to the surface ridges is incorr ect. Rather than decreases in intensity in particular scattering geome tries due to modes being forbidden, the observed intensity variations with azimuth appear as a result of intensity increases, in particular for out-of-plane modes when the scattering is perpendicular to the mol ecular plane. (C) 1998 Elsevier Science B.V. All rights reserved.