Identification Of A Critical Intermediate In Galvanic Exchange Reactions By Single-nanoparticle Resolved Kinetics

Smith, Jeremy George

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https://hdl.handle.net/2142/50813 Copy

Description

Title

Identification Of A Critical Intermediate In Galvanic Exchange Reactions By Single-nanoparticle Resolved Kinetics

Author(s)

Smith, Jeremy George

Contributor(s)

Jain, Prashant

Issue Date

2014-06-17

Keyword(s)

Mini-symposium: Spectroscopy in Kinetics and Dynamics

Abstract

\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.25]{Graph2.eps} \end{wrapfigure} The realization of common materials transformations in nanocrystalline systems is fostering the development of novel nanostructures and allowing a deep look into the atomistic mechanisms involved. Galvanic corrosion is one such transformation. We studied galvanic replacement within individual metal nanoparticles by using plasmonic spectroscopy. This proved to be a powerful approach to studying materials transformations in the absence of ensemble averaging. Individual nanoscale units act as domains that can be interrogated optically in isolation, whereas the averaging of all such domains provides a bulk reaction trajectory. Single-nanoparticle reaction trajectories showed that a Ag nanoparticle exposed to Au$^{3+}$ makes an abrupt transition into a nanocage structure. The transition is limited by a critical structural event, which we identified by electron microscopy to comprise the formation of a nanosized void, similar to the pitting process commonly observed in the corrosion of metals. Trajectories also revealed a surprisingly strong nonlinearity of the reaction kinetics, which we explain by a model involving the critical coalescence of vacancies into a growing void. The critical void size for galvanic exchange to spontaneously proceed was found to be 20 atomic vacancies. In the future we hope to extend this approach to examine a wide variety of materials transformations and chemical reactions.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/50813

DOI

https://doi.org/10.15278/isms.2014.TH09

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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