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A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions
Published on: February 5, 2016
Optically excited acoustic vibrations in quantum-sized monolayer-protected gold clusters
Oleg Varnavski1, Guda Ramakrishna, Junhyung Kim
1Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
ACS Nano
|June 1, 2010
Summary
Optically excited vibrations in gold nanoclusters (< or =2.2 nm) were size-independent. Larger gold clusters (3-4 nm) showed no detectable vibrations, suggesting a displacive excitation mechanism in quantum-sized nanoclusters.
Area of Science:
- Physical Chemistry
- Materials Science
- Nanotechnology
Background:
- Monolayer-protected gold clusters exhibit quantum size effects.
- Understanding vibrational dynamics is crucial for characterizing nanocluster properties.
Purpose of the Study:
- To systematically investigate optically excited vibrations in gold nanoclusters.
- To determine the influence of cluster size on vibrational frequencies.
- To explore excitation and detection mechanisms of vibrations in nanoclusters.
Main Methods:
- Transient absorption experiments using 50 fs light pulses.
- Systematic variation of gold cluster size (1.1-4 nm).
- Analysis of vibrational frequencies as a function of particle size.
Main Results:
- Vibrational frequencies were size-independent for clusters <= 2.2 nm.
- No detectable optically excited vibrations were observed for clusters of 3 and 4 nm.
- Results support a displacive excitation mechanism linked to the optical energy gap.
Conclusions:
- Optically excited vibrations offer a diagnostic tool for quantum size effects.
- Vibrational analysis aids in structural studies of metal nanoclusters.
- The findings provide insights into the fundamental physics of quantum-sized nanoclusters.
