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Dynamic structure factor of density fluctuations from direct imaging very near (both above and below) the critical point of SF6

hal.structure.identifierDepartment of Physics and Astronomy [Charleston]
dc.contributor.authorOPRISAN, Ana
hal.structure.identifierDepartment of Physics and Astronomy [Charleston]
dc.contributor.authorOPRISAN, Sorinel Adrian
hal.structure.identifierDepartment of Physics and Astronomy [Charleston]
dc.contributor.authorBAYLEY, Brittany
hal.structure.identifierDepartment of Physics [New Orleans]
dc.contributor.authorHEGSETH, John
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorGARRABOS, Yves
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorLECOUTRE-CHABOT, Carole
hal.structure.identifierESEME : Équipe du Supercritique pour l'Environnement, les Matériaux et l'Espace : Équipe commune CEA-CNRS (2000-2014)
hal.structure.identifierPhysique et mécanique des milieux hétérogènes [PMMH]
hal.structure.identifierService des Basses Températures [SBT ]
dc.contributor.authorBEYSENS, Daniel
dc.date.issued2012
dc.identifier.issn1539-3755
dc.description.abstractEnLarge density fluctuations were observed by illuminating a cylindrical cell filled with sulfur hexafluoride (SF6), very near its liquid-gas critical point (|T−Tc|<300 μK) and recorded using a microscope with 3 μm spatial resolution. Using a dynamic structure factor algorithm, we determined from the recorded images the structure factor (SF), which measures the spatial distribution of fluctuations at different moments, and the correlation time of fluctuations. This method authorizes local measurements in contrast to the classical scattering techniques that average fluctuations over the illuminating beam. We found that during the very early stages of phase separation the SF scales with the wave vector q according to the Lorentzian q−2, which shows that the liquid and vapor domains are just emerging. The critical wave number, which is related to the characteristic length of fluctuations, steadily decreases over time, supporting a sustained increase in the spatial scale of the fluctuating domains. The scaled evolution of the critical wave number obeys the universal evolution for the interconnected domains at high volume fraction with an apparent power law exponent of −0.35 ± 0.02. We also determined the correlation time of the fluctuations and inferred values for thermal diffusivity coefficient very near the critical point, above and below. The values were used to pinpoint the crossing of Tc within 13 μK.
dc.language.isoen
dc.publisherAmerican Physical Society
dc.title.enDynamic structure factor of density fluctuations from direct imaging very near (both above and below) the critical point of SF6
dc.typeArticle de revue
dc.identifier.doi10.1103/PhysRevE.86.061501
dc.subject.halChimie/Matériaux
bordeaux.journalPhysical Review E : Statistical, Nonlinear, and Soft Matter Physics
bordeaux.page061501 (7 p.)
bordeaux.volume86
bordeaux.issue6
bordeaux.peerReviewedoui
hal.identifierhal-00761578
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00761578v1
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