Infrared Attenuated Total Reflection Spectroscopy
for the Characterization of Gold Nanoparticles in Solution
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Abstract
In
situ synthesis of bare gold nanoparticles mediated by stainless
steel as reducing agent was monitored via infrared attenuated total
reflection (IR-ATR) spectroscopy. Gold nanoparticles were directly
synthesized within the liquid cell of the ATR unit taking immediate
advantage of the stainless steel walls of the ATR cell. As nanoparticles
were formed, a layer of particles was deposited at the SiO<sub>2</sub> ATR waveguide surface. Incidentally, the absorption bands of water
increased resulting from surface-enhanced infrared absorption (SEIRA)
effects arising from the presence of the gold nanoparticles within
the evanescent field. Next to the influence of the Au(III) precursor
concentration and the temperature, the suitability of IR-ATR spectroscopy
as an innovative tool for investigating changes of nanoparticles in
solution, including their aggregation promoted by an increase of the
ionic strength or via a pH decrease, and for detailing the sedimentation
process of gold nanoparticles was confirmed