Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 68: Polymeric biomolecular films

O 68.7: Talk

Thursday, March 17, 2011, 12:45–13:00, WIL B122

The effect of chain-length on the branching of irradiation-induced processes in alkanethiolate molecular films — •Frederick Chesneau, Hicham Hamoudi, and Michael Zharnikov — Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany

The effect of X-ray and low-energy (50 eV) electron irradiation on short-chain alkanethiolate (AT) self-assembled monolayers (SAMs) on Au(111) was studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and infrared reflection absorption spectroscopy. As a test system, a SAM of hexanethiolate (C6) was used. An analogous long-chain film, dodecanethiolate (C12) SAM, was taken as reference. Whereas both C6 and C12 films exhibited a full range of irradiation-induced reactions characteristic of AT SAMs on coinage metal substrates, the branching of the reactions in these two systems was distinctly different. Whereas in the case of C12/Au, the dominant processes were decomposition of the alkyl chains and capture of the released alkylsulfide moieties in the aliphatic matrix, desorption of the complete molecular species emerging after the cleavage of the thiolate-gold bond prevailed in the case of C6/Au. A tentative explanation for this behavior will be proposed.