Single-nanocrystal reaction trajectories reveal sharp cooperative transitions

Aaron L. Routzahn, Prashant K. Jain

Research output: Contribution to journalArticle

Abstract

Whereas pathways of chemical reactions involving small molecules are well-understood, the 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 such as critical nucleation phenomena or sharp phase transitions occurring within individual, often nanoscale, grains, or domains. By optically monitoring a solid-state reaction with single nanocrystal resolution, we directly identified a unique, previously unknown, reaction pathway. Reaction trajectories of single cadmium selenide nanocrystals undergoing ion exchange with silver reveal that each individual nanocrystal waits a unique amount of time before making an abrupt switch to the silver selenide phase on a few hundred millisecond time scale. The gradual reaction progress of ensemble-scale cation exchange is actually comprised of these sharp single-nanocrystal switching events. Statistical distributions of waiting times suggest that the reaction is a cooperative transition rather than a diffusion-limited cation-by-cation exchange, which is confirmed by a stochastic reaction model. Such insight, achievable from single nanocrystal reaction studies, furthers mechanistic understanding of heterogeneous reactions, solid-state catalysis, bottom-up nanostructure growth, and materials' transformations and degradation in reactive environments.

Original languageEnglish (US)
Pages (from-to)987-992
Number of pages6
JournalNano letters
Volume14
Issue number2
DOIs
StatePublished - Feb 12 2014

Fingerprint

Nanocrystals
nanocrystals
Trajectories
trajectories
Cations
Ion exchange
Positive ions
Solid state reactions
Silver
cations
Cadmium
Catalysis
Chemical reactions
Nanostructures
nanostructure growth
silver
Nucleation
Phase transitions
solid state
cadmium selenides

Keywords

  • cation exchange
  • CdSe/CdS
  • cooperativity
  • nucleation
  • Quantum dot
  • single-particle spectroscopy

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Single-nanocrystal reaction trajectories reveal sharp cooperative transitions. / Routzahn, Aaron L.; Jain, Prashant K.

In: Nano letters, Vol. 14, No. 2, 12.02.2014, p. 987-992.

Research output: Contribution to journalArticle

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