Self assembled monolayers of rigid thiols on Gold

Self assembled monolayers (SAM) of $\omega $-functionalized mercaptobiphenyls ($\omega $-MBP) are stable, molecularly engineered ultrathin organic films, which can be used for the design of model surfaces with well-defined chemical and physical properties. For example, the number and distribution of terminal hydroxyl groups can be tailored to study water-surface interactions or the chemisorption of organic molecules from solution. We have prepared and studied SAM of mercaptobiphenyls (MBP), 4-Methyl-4'-MBP, and 4-Hydroxy-4'-MBP on Au (111). The film quality of the SAM with respect to coverage and structure was characterized by contact angle measurements, spectral ellipsometry, infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and sum frequency generation. By means of a frequency analysis based on ab initio calculations, the different vibrational modes could be assigned and used for the study of chemisorption processes at the surface.