{"id":3970,"date":"2025-01-14T10:40:07","date_gmt":"2025-01-14T09:40:07","guid":{"rendered":"https:\/\/equipes.lps.u-psud.fr\/matrix\/?p=3970"},"modified":"2025-01-17T09:12:22","modified_gmt":"2025-01-17T08:12:22","slug":"no-need-to-hit-the-iron-while-its-small","status":"publish","type":"post","link":"https:\/\/equipes.lps.u-psud.fr\/matrix\/no-need-to-hit-the-iron-while-its-small\/","title":{"rendered":"No need to hit the iron while it\u2019s… small!"},"content":{"rendered":"\n

Scientists from CNRS have studied the shape evolution of gold nano-tetrapods and revealed a two-step kinetics process: the four arms\u2014initially sharp\u2014quickly blunt, followed by a slow retraction towards an almost spherical final shape.<\/strong><\/em><\/p>\n\n\n\n

Deforming macroscopic metallic objects requires considerable force. At the nanoscale, however, things are quite different: surface forces alone are often sufficient to reshape nanoparticles, guiding them towards the most energetically favorable form. Understanding this “nano-metallurgy” is crucial not only for advancing fundamental knowledge but also for driving progress in nanotechnology. Yet, the processes involved are challenging to monitor in real-time.<\/p>\n\n\n\n

A team of researchers from several French and European laboratories [1] recently published a detailed study in Nano Letters<\/em> on the transformation pathway of metastable gold particles, initially featuring four sharp arms, into nearly spherical particles. Thanks to their well-defined geometry, these “nano-tetrapods” are easier to study than “nanostars,” which have similar characteristics but more varied morphologies. By combining electron microscopy, X-ray scattering, optical spectroscopy techniques, and advanced data processing, the researchers uncovered a complex kinetic process. This begins with a rapid flattening of the tips towards a {110} facet of gold\u2019s crystalline lattice, followed by a slower reshaping phase into an isometric form.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure.<\/strong> Schematic representation of the temporal evolution (indicated by the arrow) of a nano-tetrapod, from its initial sharp state to a truncated form with arms defined by {110} facets, and finally to a rounded, quasi-spherical final state. This transformation was monitored in solution using small-angle X-ray scattering (SAXS) and UV-Vis optical absorption spectroscopy. Complementary studies using transmission electron microscopy (TEM) were conducted in the dry state.<\/p>\n\n\n\n

Beyond the conceptual understanding of their evolution, this study will enable the use of these nano-objects in nonlinear optical applications [2], thanks to their unique shape, which lacks a center of inversion.<\/p>\n\n\n\n

<\/p>\n\n\n\n

[1] Damien Alloyeau at Laboratoire Mat\u00e9riaux et Ph\u00e9nom\u00e8nes Quantiques, (Universit\u00e9 Paris Cit\u00e9\/CNRS), le Laboratoire de physique des solides (CNRS\/Universit\u00e9 de Paris-Saclay), Doru Constantin at l’Institut Charles Sadron (CNRS\/Universit\u00e9 de Strasbourg) and the European synchrotron ESRF (Grenoble).<\/p>\n\n\n\n

[2] Jieli Lyu et al., Shape-Controlled Second-Harmonic Scattering from Gold Nanotetrapods, J. Phys. Chem. C<\/em> 126<\/strong>, 9831-9835<\/a> (2022).<\/p>\n\n\n\n

Reference<\/strong>
Jieli Lyu et al., Two-step reshaping of acicular gold nanoparticles, Nano Letters<\/em> (2025).
DOI: 10.1021\/acs.nanolett.4c05601<\/a><\/p>\n\n\n\n

Contact<\/strong>\u00a0: Cyrille Hamon<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Scientists from CNRS have studied the shape evolution of gold nano-tetrapods and revealed a two-step kinetics process: the four arms\u2014initially sharp\u2014quickly blunt, followed by a slow retraction towards an almost …<\/p>\n","protected":false},"author":25,"featured_media":3971,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-3970","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-publication"],"_links":{"self":[{"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/posts\/3970","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/users\/25"}],"replies":[{"embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/comments?post=3970"}],"version-history":[{"count":2,"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/posts\/3970\/revisions"}],"predecessor-version":[{"id":3973,"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/posts\/3970\/revisions\/3973"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/media\/3971"}],"wp:attachment":[{"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/media?parent=3970"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/categories?post=3970"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/matrix\/wp-json\/wp\/v2\/tags?post=3970"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}