jp0c01844_si_001.mp4 (7.07 MB)
Microscopic Analysis of Heterogeneous Nucleation of Nanoparticle Superstructures
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posted on 2020-04-23, 19:14 authored by Ann-Kathrin Göppert, Guillermo González-Rubio, Helmut CölfenNucleation
phenomena play an important role in our world, and understanding
them is of major interest. However, we lack analytical methods with
the sufficient temporal and spatial resolution to analyze nucleation
processes. In this work we used CTAB-stabilized gold nanocubes as
a model system for nucleation, meaning the nanoparticles act like
ions or atoms and built up larger superstructures comparable to normal
nucleation phenomena. Thereby we analyzed the heterogeneous nucleation
of the gold nanocubes on hydrophobized and negatively charged mica
surfaces with a combination of UV–vis–NIR spectroscopy
and light microscopy. With the plasmon resonance of the gold nanocubes
we gained valuable information about the early nucleation of the particles
and their concentration in solution via UV–vis–NIR spectroscopy.
The combination with a light microscope enabled the simultaneous detection
of nucleated species on the surfaces and opened the possibility to
analyze the kinetics of the heterogeneous nucleation process. With
this, we were able to determine the nucleation rates. While the hydrophobized
surfaces did not influence the nucleation of the gold nanocubes, the
negatively charged surfaces greatly promoted the nucleation. Thereby,
we could demonstrate that the combination of simple and commonly available
light microscopy and optical spectroscopies in general is a suitable
and easy strategy to analyze heterogeneous nucleation processes directly
in solution on a relevant statistical basis.