title: Shape resonances of oriented molecules: ab initio theory and experiment on hydrocarbon molecules
abstract: We report ab initio calculations of the x-ray absorption cross section for the near edge x-ray absorption fine structure of C2H6, and C2H4, and C2H2 at the C K-edge, based on a full multiple scattering formalism. The angular dependence of the electric dipole transition in the calculations as well as the angular dependent experiments for the oriented molecules give a good opportunity to compare both. The resonance can be assigned to a sigma(*) shape resonance. The multiple scattering formalism and the experiment agree well and thereby support the existence of such features in the spectra.
authors.affiliation: Institut fur Experimentalphysik, Freie Universitat Berlin, Arnimallee 14, D-14195 Berlin-Dahlem, Germany.
authors.initials: N
authors.lastname: Haack
authors.initials: G
authors.lastname: Ceballos
authors.initials: H
authors.lastname: Wende
authors.initials: K
authors.lastname: Baberschke
authors.initials: D
authors.lastname: Arvanitis
authors.initials: AL
authors.lastname: Ankudinov
authors.initials: JJ
authors.lastname: Rehr