The orientation and electronic structure of 1,3-butadiene adsorbed and condensed on Ag(110): a NEXAFS study

Abstract

The orientation of butadiene molecules at submonolayer coverage on Ag(110) has been investigated by near edge X-ray absorption fine structure spectroscopy. The polarization dependence of the C1s → π* excitation was measured, and the integral intensity of this transition was used to determine that butadiene chemisorbs with its σh plane parallel to the plane of the surface. By comparison of the energy of the C1s → σ* shape resonance for the chemisorbed molecule to that of the gas phase and condensed multilayer the CC and C-C bond lengths were found to be identical to the gas phase values of 1.34 and 1.46 Å, respectively. A polarization dependence of the π* resonances was also found in the condensed multilayer and is identified with ordering of the molecules such that the π orbitals are perpendicular to the surface. © 1991.