[MOS] April 1, 2014, Prashant K. Jain, University of Illinois at Urbana Champaign

[Zina M Queen]

Seminar on

Modern Optics and Spectroscopy

 

Deciphering Chemistry on the Nanoscale by Optical Imaging

 

Prashant K. Jain,

University of Illinois at Urbana Champaign


Tuesday, April 1, 2014

12:00 – 1:00 p.m.

Whereas pathways of chemical reactions involving small molecules are well understood, dynamics of reactions in extended solids remain difficult to elucidate. Frequently, kinetic studies on bulk materials provide a picture averaged over multiple domains or grains, smearing out interesting dynamics occurring within individual, often nanoscale, domains. My lab employs in-situ single-particle optical spectroscopy to decipher from single-particle trajectories previously unknown information about dynamical pathways or nucleation in a solid-state transformation. Recently, by optically monitoring a solid-state reaction with single nanocrystal resolution, we directly identified a new reaction pathway. Trajectories of single CdSe nanocrystals reacting with Ag revealed sharp single-nanocrystal switching events, suggesting that the reaction is a co-operative transition rather than a diffusion-limited process. I will give two more examples (thiol self-assembly and galvanic corrosion) to demonstrate that single nanocrystal reaction studies can further mechanistic understanding of heterogeneous reactions, solid-state catalysis, bottom-up nanostructure growth, and materials' degradation in reactive environments.
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