A momentum space view of the surface chemical bond.

Well-ordered and oriented monolayers of conjugated organic molecules can offer new perspectives on surface bonding. We will demonstrate the importance of the momentum distribution, or symmetry, of the adsorbate molecules' π orbitals in relation to the states available for hybridization at the metal surface. Here, the electronic band structure of the first monolayer of sexiphenyl on Cu(110) has been examined in detail with angle-resolved ultraviolet photoemission spectroscopy over a large momentum range and will be compared to measurements of a multilayer thin film and to density functional calculations.

Pre-nucleation dynamics of organic molecule self-assembly investigated by PEEM.

Pre-nucleation dynamics, nucleation and templated self-assembly of a conjugated planar aromatic molecule are investigated by photoemission electron microscopy (PEEM). The high resolution of individual molecular layers in PEEM, in combination with a numerical simulation, reveals the dynamic behaviour of molecules during the pre-nucleation deposition period and their temperature dependence. The in situ deposition of p-sexiphenyl (6P) molecules on Cu(110) and Cu(110) 2 × 1-O surfaces in ultrahigh vacuum, when monitored by PEEM in real-time allows (a) layer densities, (b) meta-stable layer filling by 6P molecules, (c) dynamic surface redistributions during layer filling and (d) critical density spontaneous dewetting to be accurately measured.

Reconstruction of molecular orbital densities from photoemission data.

Photoemission spectroscopy is commonly applied to study the band structure of solids by measuring the kinetic energy versus angular distribution of the photoemitted electrons. Here, we apply this experimental technique to characterize discrete orbitals of large pi-conjugated molecules. By measuring the photoemission intensity from a constant initial-state energy over a hemispherical region, we generate reciprocal space maps of the emitting orbital density.