Imaging transient melting of a nanocrystal using an X-ray laser

Jesse N. Clark, Loren Beitra, Gang Xiong, David M. Fritz, Henrik T. Lemke, Diling Zhu, Matthieu Chollet, Garth J. Williams, Marc Messerschmidt, Brian Abbey, Ross J. Harder, Alexander M. Korsunsky, Justin S. Wark, David A. Reis, Ian K. Robinson

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

There is a fundamental interest in studying photoinduced dynamics in nanoparticles and nanostructures as it provides insight into their mechanical and thermal properties out of equilibrium and during phase transitions. Nanoparticles can display significantly different properties from the bulk, which is due to the interplay between their size, morphology, crystallinity, defect concentration, and surface properties. Particularly interesting scenarios arise when nanoparticles undergo phase transitions, such as melting induced by an optical laser. Current theoretical evidence suggests that nanoparticles can undergo reversible nonhomogenous melting with the formation of a core-shell structure consisting of a liquid outer layer. To date, studies from ensembles of nanoparticles have tentatively suggested that such mechanisms are present. Here we demonstrate imaging transient melting and softening of the acoustic phonon modes of an individual gold nanocrystal, using an X-ray free electron laser. The results demonstrate that the transient melting is reversible and nonhomogenous, consistent with a core-shell model of melting. The results have implications for understanding transient processes in nanoparticles and determining their elastic properties as they undergo phase transitions.

Original languageEnglish (US)
Pages (from-to)7444-7448
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume112
Issue number24
DOIs
StatePublished - Jun 16 2015
Externally publishedYes

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Keywords

  • Coherent diffraction
  • Phase transition
  • Pump-probe
  • Ultrafast imaging
  • X-ray laser

ASJC Scopus subject areas

  • General

Cite this

Clark, J. N., Beitra, L., Xiong, G., Fritz, D. M., Lemke, H. T., Zhu, D., Chollet, M., Williams, G. J., Messerschmidt, M., Abbey, B., Harder, R. J., Korsunsky, A. M., Wark, J. S., Reis, D. A., & Robinson, I. K. (2015). Imaging transient melting of a nanocrystal using an X-ray laser. Proceedings of the National Academy of Sciences of the United States of America, 112(24), 7444-7448. https://doi.org/10.1073/pnas.1417678112