This image was selected for the "Back
Scatter" back cover feature of Physics Today, Vol. 62, No. 2 (Feb. 2009)
Mixed self-assembled monolayers (SAMs) offer the intriguing possibility of tailoring wetting properties, surface energy, and
other interfacial characteristics by combining suitable molecular constituents. This atomic force micrograph, 800 nm tall, shows
the onset of nanoscopic phase separation in an ideally mixed two-component SAM. The small domains of each material can be distinguished
with topographic contrast because of their 2-Å length difference. The larger domains are due to atomic terracing of the
underlying gold surface.
Seth Darling (CNM) and Steven Sibener (University of Chicago) are working to understand the stages of phase separation in such
mixed SAMs to gain insights into surface-property modifications. The molecules used in the study were synthesized by Dong-Chan
Lee and Luping Yu (both at University of Chicago).