Marcus U Witt, G H Philipp Nguyen, Josefine R von Puttkamer-Luerssen, Can H Yilderim, Johannes A B Wagner, Ebrahim Malek, Sabrina Juretzka, Jorge L Meyrelles, Maximilan Hofmann, Hartmut Löwen, Thomas Palberg
{"title":"Accessing the free expansion of a crystalline colloidal drop by optical experiments.","authors":"Marcus U Witt, G H Philipp Nguyen, Josefine R von Puttkamer-Luerssen, Can H Yilderim, Johannes A B Wagner, Ebrahim Malek, Sabrina Juretzka, Jorge L Meyrelles, Maximilan Hofmann, Hartmut Löwen, Thomas Palberg","doi":"10.1039/d4sm00413b","DOIUrl":null,"url":null,"abstract":"<p><p>We study poly-crystalline spherical drops of an aqueous suspension of highly charged colloidal spheres exposed to a colloid-free aqueous environment. Crystal contours were obtained from standard optical imaging. The crystal spheres first expand to nearly four times their initial volume before slowly shrinking due to dilution-induced melting. Exploiting coherent multiple-scattering by (110) Bragg reflecting crystals, time-dependent density profiles were recorded within the drop interior. These show a continuously flattening radial density gradient and a decreasing central density. Expansion curves and density profiles are qualitatively consistent with theoretical expectations based on dynamical density functional theory for the expansion of a spherical crystallite made of charged Brownian spheres. We anticipate that our study opens novel experimental access to density determination in turbid crystals.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Soft Matter","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1039/d4sm00413b","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
We study poly-crystalline spherical drops of an aqueous suspension of highly charged colloidal spheres exposed to a colloid-free aqueous environment. Crystal contours were obtained from standard optical imaging. The crystal spheres first expand to nearly four times their initial volume before slowly shrinking due to dilution-induced melting. Exploiting coherent multiple-scattering by (110) Bragg reflecting crystals, time-dependent density profiles were recorded within the drop interior. These show a continuously flattening radial density gradient and a decreasing central density. Expansion curves and density profiles are qualitatively consistent with theoretical expectations based on dynamical density functional theory for the expansion of a spherical crystallite made of charged Brownian spheres. We anticipate that our study opens novel experimental access to density determination in turbid crystals.