Interfacial electronic structure of long-chain alkane/metal systems studied by UV-photoelectron and metastable atom electron spectroscopies

Electronic structure and molecular orientation at the interface formed by depositing a monolayer film of tetratetracontane (TTC, n-CH3(CH2)42CH3) on metals (Au, Ag and Pb) were investigated by ultraviolet photoelectron (UP) spectroscopy and metastable atom electron (MAE) spectroscopy. The MAE spectra reveal that the TTC molecules lie parallel to the substrate surface. A change in the work function by TTC deposition is observed in the UP spectra. The electronic polarization in the molecule is proposed as a possible origin of this change. In contrast to the change of the work function, the HOMO energy of TTC is found to be independent of the coverage up to the first monolayer.