Subsecond Self-Assembled Monolayer Formation

We have observed and investigated the ultrafast self-assembly of 1-adamantanethiol (AdSH) molecules on gold at room temperature and at 393K by scanning tunneling microscopy and X-ray photoelectron spectroscopy. Rapid high-temperature adsorption was shown to yield a well-ordered defect-free hexagonal packed layer of AdSH molecules. The demonstrated subsecond self-assembly dramatically reduces the time required to form such a layer and provides an impetus to expand the application of self-assembled monolayers in areas, such as surface passivation/functionalization, sensors, catalysis, and electronics. The chemisorbed AdSH molecules have been investigated at a single-molecule level using ambient STM. Near atomic resolution STM images allowed the determination of the preferred molecular conformation on the gold and the molecular tilt (114 degrees) and the twist (0 degrees) angles. On the basis of these findings, a detailed molecular model for assembled AdSH molecules on gold is proposed.