Electronic structure of alkane chains. Complete one-dimensional band structures of the valence states

Several ultrathin films of oriented alkane chains were studied by ultraviolet photoelectron spectroscopy using UV photons in the energy range of 20-200 eV. From the experimental data the full valence band structure has been determined for self-assembled films of long-chain n-alkanethiols, Langmuir-Blodgett films of Cd-arachidate and thin films of hexatriacontane. Significant deviations from band structures obtained by ab initio calculations of Karpfen are found at the boundary of the one-dimensional Brillouin zone. Furthermore it is demonstrated that a mapping of the one-dimensional band structure can be used for precisely determining tilt angles of alkane chains.