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 Title: Identification Of A Critical Intermediate In Galvanic Exchange Reactions By Single-nanoparticle Resolved Kinetics Author(s): Smith, Jeremy George Contributor(s): Jain, Prashant Subject(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. Issue Date: 2014-06-17 Publisher: International Symposium on Molecular Spectroscopy Citation Info: Smith, J.G.; Jain, P. IDENTIFICATION OF A CRITICAL INTERMEDIATE IN GALVANIC EXCHANGE REACTIONS BY SINGLE-NANOPARTICLE RESOLVED KINETICS. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014. DOI: 10.15278/isms.2014.TH09 Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/50813 DOI: https://doi.org/10.15278/isms.2014.TH09 Rights Information: Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/ Date Available in IDEALS: 2014-09-172015-04-14
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