Electronic structure and orientation of anthracene on Ag(111)

Spectroscopic techniques based on photoabsorption and photoemission, i.e. near edge X-ray absorption fine structure (NEXAFS) and angular-resolved photoemission (ARUPS) using synchrotron radiation, as well as inverse photoemission (IPES) have been employed to obtain information on the molecular orientation and electronic structure of thin films of anthracene adsorbed on Ag(111) surfaces. By measuring the polarisation dependence of the (Cls →π∗) transitions in the NEXAFS spectra, we find a parallel orientation of the molecular plane with respect to the substrate. The angular behaviour of the adsorbate-induced photoemission bands corroborates this result, and additionally a complete mapping of the valence levels and an improved assignment for the bands extended over a large binding energy region emerges. The unoccupied π ∗ levels levels have been studied by inverse photoemission and have been compared with MO calculations, as well as with electron transmission gas phase measurements (ETS). A well ordered (4 × 4) structure is observed in LEED investigations

Azimuthal orientation of tetracene adsorbed on Cu(110) single crystal surfaces

Angular resolved photoemission spectroscopy using synchrotron radiation from the BESSY storage ring has been employed to investigate the geometrical arrangement of tetracene molecules adsorbed on Cu(110) surfaces. By simple symmetry considerations based on dipole selection rules we find a perpendicular orientation of the molecules with their molecular planes aligned along the [1̄10] azimuth. Additionally, a c(4 × 2) structure has been observed by LEED

Electronic structure and orientation of tetracene on Cu(100)AB

Angular resolved photoemission spectroscopy using synchrotron radiation (10 eV≤hv≤45 eV) yields a detailed picture of the electronic structure of the valence bands and information concerning the orientation of thin films of tetracene adsorbed at room temperature on Cu(100) substrates. With LEED a well ordered 2×2 overlayer is observed. Dipole selection rules based on the molecular symmetry have been used in order to analyze the angular-dependence of the observed photoemission bands. We find a perpendicular orientation of the tetracene molecular plane with respect to the Cu(100) substrate and arrive at a detailed assignment of all valence band features in good agreement with MO calculations

Unoccupied electronic structure of phthalocyanine films

The unoccupied molecular orbitals of metal‐free phthalocyanine (H2PC), nickel‐phthalocyanine (NiPC), and copper‐phthalocyanine (CuPC) adsorbed on single crystal surfaces have been studied by inverse photoemission spectroscopy (IPES) and near‐edge x‐ray absorption spectroscopy (NEXAFS). The features observed in the experimental data are assigned by reference to molecular orbital calculations. Carbon and nitrogen 1s NEXAFS measurements of NiPC adsorbed on Cu(110) surface indicates that the phthalocyanine molecular planes are parallel to the surface. X‐ray absorption data recorded at the Ni LIII and LII edges show that the unoccupied Ni 3d level is located in the plane of the phthalocyanine rings