eprintid: 1487278 rev_number: 28 eprint_status: archive userid: 608 dir: disk0/01/48/72/78 datestamp: 2016-05-01 16:05:25 lastmod: 2021-09-26 22:35:53 status_changed: 2016-08-12 10:25:05 type: article metadata_visibility: show creators_name: Clark, JN creators_name: Beitra, L creators_name: Xiong, G creators_name: Fritz, DM creators_name: Lemke, HT creators_name: Zhu, D creators_name: Chollet, M creators_name: Williams, GJ creators_name: Messerschmidt, MM creators_name: Abbey, B creators_name: Harder, RJ creators_name: Korsunsky, AM creators_name: Wark, JS creators_name: Reis, DA creators_name: Robinson, IK title: Imaging transient melting of a nanocrystal using an X-ray laser ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F64 keywords: X-ray laser, coherent diffraction, phase transition, pump-probe, ultrafast imaging 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. date: 2015-06-16 date_type: published official_url: http://dx.doi.org/10.1073/pnas.1417678112 oa_status: green full_text_type: other pmcid: PMC4475963 language: eng primo: open primo_central: open_green article_type_text: Journal Article verified: verified_manual elements_id: 1053328 doi: 10.1073/pnas.1417678112 pii: 1417678112 lyricists_name: Robinson, Ian lyricists_id: IKROB22 full_text_status: public publication: Proceedings of the National Academy of Sciences of the United States of America volume: 112 number: 24 pagerange: 7444-7448 event_location: United States issn: 1091-6490 citation: Clark, JN; Beitra, L; Xiong, G; Fritz, DM; Lemke, HT; Zhu, D; Chollet, M; ... Robinson, IK; + view all <#> Clark, JN; Beitra, L; Xiong, G; Fritz, DM; Lemke, HT; Zhu, D; Chollet, M; Williams, GJ; Messerschmidt, MM; Abbey, B; Harder, RJ; Korsunsky, AM; Wark, JS; Reis, DA; Robinson, IK; - view fewer <#> (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) pp. 7444-7448. 10.1073/pnas.1417678112 <https://doi.org/10.1073/pnas.1417678112>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/1487278/1/Robinson_Jesse_lcls_melting_v1.pdf