A high resolution electron energy loss spectroscopy study of the adsorption of benzylic amide macrocycle on Au(111)

The adsorption from the gas phase of a macrocyclic molecule composed of ben zylic amide (-CONH-CH2-C6H4-) groups on Au(1 1 1) at 300 K has been studied using high resolution electron energy loss spectroscopy. The film order an d vibrational properties were explored as a function of coverage, method of adlayer deposition and annealing. Beyond a critical coverage, a template e ffect strongly influences the macrocycle's orientation with respect to the substrate. In the case of ordered films (domain size > 80 Angstrom), the in tensity of the out-of-plane C-H deformation mode relative to the in-plane C -H stretch indicates that an adsorption geometry with the plane of the phen yl rings largely parallel to the Au(1 1 1) surface is favoured in the submo nolayer to monolayer coverage regime, Upon consideration of solid state Xra y diffraction data, this flat-lying molecular orientation, which is accompa nied by chemisorption via the carbonyl function, must involve considerable distortion of the adsorbed macrocycle from its crystal structure. (C) 2001 Elsevier Science B.V. All rights reserved.