Nanoparticle Shape: Effects and Modeling

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• Emilie Ringe, Northwestern University, Evanston, Illinois, USA
• Wednesday 14 September 2011, 15:00-16:00
• T001 [Tower Seminar Room], Materials Science and Metallurgy, Department of.

If you have a question about this talk, please contact Caterina Ducati.

Interest in nanotechnology is driven by unprecedented properties tailorability, achievable by controlling particle structure and composition. Unlike bulk components, minute changes in size and shape affect the optical and electronic properties of nanoparticles. Characterization of such structure-function relationships and better understanding of structure control mechanisms is crucial to the development of novel applications such as plasmonic sensors and devices.

The first part of this talk will focus on new analytical models developed to understand the structure and composition of nanoparticles. One such model describes segregation effects in small (2-10 nm) alloy nanoparticles, where the thermodynamic Wulff construction becomes size dependent and the infinite reservoir approximation breaks down [1]. Another model discussed involves the interplay of surface properties and crystallographic defects on the kinetic growth of twinned nanoparticles. From this approach one can explain shapes which cannot currently be understood using thermodynamic models.

The second part will cover recent experimental advances in correlated single particle optical and structural characterization, which provide new hindsight on the effects of size and shape on plasmonic properties such as resonance frequency, field enhancement, plasmon decay, and refractive index sensitivity [2-4]. Specific results discussed include those obtained by 1) performing high throughput correlated measurements, 2) coupling single particle refractive index sensitivity measurements with spectral and structural characterization, and 3) taking advantage of large size and shape inhomogeneities to develop quantitative models for structural effects and their interplay.

[1] Ringe, E.; Van Duyne, R. P.; Marks, L. D. Nano Lett. 2011, 11, 3399. [2] Ringe, E.; McMahon, J. M.; Sohn, K.; Cobley, C. M.; Xia, Y.; Huang, J.; Schatz, G. C.; Marks, L. D.; Van Duyne, R. P. J. Phys, Chem. C 2010 , 114, 12511. [3] Henry, A.-I.; Bingham, J. M.; Ringe, E.; Marks, L. D.; Schatz, G. C.; Van Duyne, R. P. J. Phys. Chem. C 2011 , 115, 9291. [4] Kleinman, S. K.; Ringe, E.; Valley, N.; Wustholz, K. L.; Phillios, E.; Scheidt, K. A.; Schatz, G. C.; Van Duyne, R. P. J. Am. Chem. Soc. 2011, 133, 4115.

This talk is part of the Electron Microscopy Group Seminars series.

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