STM Investigations of Thiol Self-Assembled Monolayers

The most-studied thin organic monolayers—which have applications in many areas of science and technology—are self-assembled monolayers (SAMs) of alkanethiols. Scanning tunneling microscopy (STM) of alkanethiol SAMs on Au(111) surfaces reveals small holes or defects, whose origin is a current topic of discussion. The STM investigation reported here of thiosalicylic acid on Au(111) reveals not holes but disordered structures. Comparison of the two sets of measurements provides new aspects for consideration with regard to the origin of the hole defects in thiol selfassembled films.