Structure and Reactivity of Self Assembled Monolayers
STEVEN L. BERNASEK
Department of Chemistry
Princeton University
Long chain hydrocarbons
self-assemble on various substrates to make highly ordered, robust
organic thin films. The most studied prototype self-assembled
monolayer (SAM) system is the class of SAMs consisting of long chain
n-alkyl thiols adsorbed upright on gold surfaces. In contrast,
long chain hydrocarbons and substituted hydrocarbons self-assemble
parallel to the graphite surface, forming well ordered overlayers
exhibiting chirality and nano-scaled patterns. We will discuss
our recent studies of both of these types of monolayer systems.
Low energy ion scattering has been used to probe the structure and
reactivity of a series of n-alkyl thiol monolayers. An odd-even
structural effect has been observed for the reaction of the monolayers
with the incident probe ions, pyrazine and benzene. Substituted
long chain alkane molecules adsorbed on pyrolytic graphite have also
been examined, in this instance using atomic resolution scanning
tunneling microscopy. Examples of chiral structures and
monolayer structures that probe both molecule-molecule and
molecule-substrate bonding interactions will be discussed.
Several new types of chiral monolayer formation will be described.
Efforts to understand the molecule-molecule and molecule-substrate
interactions that govern structure formation will be
discussed.