p-Sexiphenyl/metal interfaces studied by photoemission and metastable atom electron spectroscopy

p-Sexiphenyl(6P)/metal (Au, Mg) interfaces were studied by ultraviolet photoemission spectroscopy (UPS), X-ray photoemission spectroscopy (XPS), and metastable atom electron spectroscopy (MAES). The vacuum level shifts (Delta) at the interface were observed in both 6P/Au (Delta=-0.8+/-0.1 eV) and 6P/Mg (Delta=-0.4+/-0.1 eV) systems. The MAES spectra indicate that the 6P molecules are on the substrate with their mean molecular plane parallel to the substrate surface in both systems, and that the 6P film on Mg substrate has some disorder. Thickness dependence of UPS, MAES, and XPS spectra suggests no significant chemical interaction for 6P on Au, Mg as well as Au, Mg on 6P interfaces. In the system of Au on 6P/Au, the spectral feature of 6P in MAES spectra did not disappear even when the thickness of evaporated gold reached 20 nm, indicating a penetration of Au atoms (or the clusters) into the 6P film. (C) 1999 Elsevier Science B.V. All rights reserved.