Influence of Nanostructure Design on the Structure and Spectroscopic Characterization of SelfAssembl

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Influence of Nanostructure Design on the
Structure and Spectroscopic Characterization of
Self-Assembled Organic Films Deposited onto Novel
Metallic Surfaces
Chad L. Leverette, Dept. of Chemistry and
Physics, USC Aiken and the USC NanoCenter, Aiken,
SC 29801
Understanding the organization and structure of
self-assembled thiol-based nanofilms on planar
metallic surfaces is an important area of
research that has led to many practical uses of
thin film technology. The incorporation and use
of novel nanostructures as substrates for these
thin film systems represents a new advancement in
this technology. However, the organization and
structure of organic films on these
nanostructures is not known. Current
understanding of organizational phenomena and
structural quality of thin films formed on
metallic surfaces has been provided by techniques
such as infrared-reflection absorption
spectroscopy (IRRAS). Significant signal
enhancements can be achieved with the use of
surface-enhanced infrared reflection-absorption
(SEIRA) spectroscopy. SEIRA involves the
enhancement of vibrations for molecules that are
in close proximity to ideally shaped metallic
nanoparticles. However, producing nanostructures
with optimal SEIRA response and understanding the
mechanisms responsible for this phenomenon is an
active area of research. Glancing angle vapor
deposition (GLAD) represents a flexible
nanofabrication technique capable of producing
various nanostructure designs that can produce
large vibrational surface enhancements. The
primary goals of this project are 1) to
fundamentally understand nanofilm organization
and structure onto non-planar metallic surfaces
2) to understand the influence of nanostructure
design on the surface-enhanced infrared
absorption enhancement phenomena, and 3) to
introduce undergraduates to nanotechnology and
involve them in the research process. Notable
outcomes to date include 1) the development of a
glancing angle vapor deposition (GLAD) system, 2)
the production of non-planar silver nanorod array
substrates that are being used to investigate
nanofilm organization and the SEIRA effect, 3)
the initial observation and characterization of
nanofilms of para-nitrobenzoic acid (p-NBA) and
para-nitrothiophenol (p-NTP) formed onto the
nanorod arrays, 4) the observation of SEIRA
enhancement with enhancement factors of 8-10, and
5) the creation of a research website to promote
this research to undergraduates, the local
community, and to the spectroscopy community as a
whole.
GLAD
570 nm nanorods
860 nm nanorods