THE PRESENCE OF 2 DIFFERENT SULFUR SPECIES IN SELF-ASSEMBLED FILMS OFN-ALKANETHIOLS ON AU AND AG SURFACES

High-resolution photoelectron spectroscopy using photon energies of 20 0 and 1486 eV is used to reveal the presence of two different sulfur s pecies in alkanethiolate films on Au and Ag surfaces. Self-assembly fr om a solution in ethanol gave similar results to vapour phase depositi on onto clean substrates in ultrahigh vacuum. In addition to chemical differences of the two S species as implied by the 1.3 eV difference i n the S 2p binding energies angular-resolved measurements revealed int ensity variations caused by photoelectron diffraction. This observatio n indicates also a geometrical inequivalence of the two sulfur species .