Synchrotron-based high-resolution X-ray photoelectron spectroscopy was for the first time applied to investigate the damage in self-assembled monolayers (SAMs) of alkanethiols (AT) on Au caused by soft X-rays. The observed changes in AT SAMs and, in particular, the appearance of a new, irradiation-induced sulfur species are identical to those caused by electron bombardment, implying that most of the damage is produced by the photoelectrons and secondary electrons. The irradiation-induced sulfur species is identified as a dialkyl sulfide distributed within the AT film. Only minutes of monochromatized X-ray irradiation at an undulator beamline destroys the AT adlayer completely.

Synchrotron-based high-resolution X-ray photoelectron spectroscopy was applied to monitor the formation of self-assembled monolayers (SAM) of alkanethiols (AT) and biphenylthiols on Au and Ag substrates. Pronounced chemical shifts in the adsorbate- and substrate-related photoemission lines upon SAM formation were observed. Only one sulfur species could be detected in the S 2p spectra of the investigated SAMs, consistent with a thiolate bond. From the fwhm's of the core level photoemission spectra conclusions on the heterogeneity of the adsorption sites and adsorption geometry can be made. The experimental data imply several (at least two) slightly different adsorption geometries for the AT moieties in AT/Au. Significant final state effects in the C 1s photoemission were found for both the aliphatic and aromatic SAMs.

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Synchrotron-based high-resolution X-ray photoelectron spectroscopy was applied to characterize self-assembled monolayers (SAM) of biphenyl-substituted alkanethiols CH 3 (C 6 H 4 ) 2 (CH 2 ) n SH (BPn, n ) 1-4) on Au and Ag substrates. Beyond previously identified odd-even changes in the packing density and the tilt angle of the biphenyl moieties, the high-resolution spectra reveal a number of additional odd-even effects upon variation of the number of methylene groups in the aliphatic part in the BPn molecule. Their occurrence and mutual correlation suggests that a BPn SAM represents a strongly correlated, highly ordered molecular assembly. In particular, periodical changes of a shake up feature in the C 1s region are observed, which are related to the differences in the arrangement of the aromatic matrix. The width and binding energy position of the S 2p signals also exhibit odd-even changes. The width changes are associated with the occupation of either equivalent or nonequivalent adsorption sites on the polycrystalline (111) Au and Ag substrates. The comparison of the width values with those for conventional alkanethiols implies that the substrate bonding of alkanethiols on gold cannot be described by a single adsorption site.

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