Mixed Methyl- and Propyl-Thiolate Monolayers on a Au(111) Surface

Mixed methyl- and propyl-thiolate self assembled monolayers (SAMs) are prepared on a Au(111) surface by exposing the gold substrate to methyl-propyl-disulfide vapor at, room temperature. Scanning tunneling microscopy imaging of such SAMs reveals a (3 x 4) phase consisting of CH3-S-Au-S-CH3, CH3-S-Au-S-(CH2)(2)CH3, and CH3-(CH2)(2)-S-Au-S-(CH2)(2)CH3. Partial desorption of methyl-thiolate occurs when samples are thermally annealed to 373 K, leading to the formation of a striped phase consisting of primarily CH3-(CH2)(2)-S-Au-S-(CH2)(2)CH3.