Angle-resolved photoemission studies of adsorbed hydrocarbons

Abstract

Angle-resolved UV photoelectron spectroscopy is used to investigate the electronic structure and bonding of adsorbed hydrocarbons, the orientation and symmetry of the adsorbate on the surface, the influence of lateral interactions, and the formation of two-dimensional adsorbate band structures. Several examples of simple hydrocarbon molecules such as benzene, ethylene and acetylene adsorbed on Ni(110), Ni(111), Ru(001) and the reconstructed surface are presented. The experimental studies are accompanied by theoretical calculations. In addition some special aspects of the photoemission process, namely the photoionization cross section and vibronic coupling, are discussed.

The adsorption of benzene on Pd(111) and ordered Sn/Pd(111) surface alloys

“…These changes are accompanied by a broadening of the band at $8 eV to higher binding energies, which is accompanied by an intensity loss on the low energy side at the same time. While the shift of the 3a 1g -orbital can be explained by dispersion, the other features point to a change in the adsorption geometry of the benzene [39].…”

“…Owing to this the assignment of the electronic states of the adsorbed benzene was performed taking into account the ARUPS studies of Steinr€ uck et al [39] (see Table 2). The decomposition reveals that the relative energetic positions of the low-lying r-orbitals 3e 1u , 1b 2u , 2b 1u and 3a 1g are virtually equal to those in the condensed phase, while the two p-orbitals are shifted to higher binding energies by $1.8 eV (1e 1g ) and $1.2 eV (1a 2u ) with respect to these orbitals clearly indicating a p-bonding of the molecule.…”

Complete determination of molecular orbitals by measurement of phase symmetry and electron density

“…The PTCDA molecule has C 2u symmetry, that is, the individual orbitals are characterized by a twofold rotational symmetry and two mirror planes normal to the molecular plane 25,26 . The four different basis functions for the initial state A 1 , A 2 , B 1 , B 2 of the C 2u symmetry group show characteristic dichroism signals, because their handedness is different.…”

Comparison of the electronic structure of two polymers with strong dipole ordering

“…where the value of k || (the wavevector parallel with the surface) can be calculated from the kinetic energy (E kin ) of the incident electron and the incidence angle θ, in the case of inverse photoemission [8,9,[17][18][19].…”