0000000001110843

AUTHOR

Andreas Heymann

showing 3 related works from this author

Particle characterization using multiple scattering decorrelation methods: hard-sphere model system

2000

Applying static light scattering experiments, we characterize colloidal particles that are used as model hard-sphere systems in experiments investigating their crystallization kinetics. The particles comprise of a compact core of poly(methyl methacrylate) and short polymer hairs grafted onto the surface. We use a contrast variation procedure to determine the refractive index variation within the particles and observe that one component of the binary mixture used as a solvent penetrates the particles and masks completely the small polymer hairs. Making use of the determined refractive index variation, we obtain the average particle radius and its polydispersity from measurements of the parti…

Materials scienceScatteringbusiness.industryMultiangle light scatteringMolecular physicsSmall-angle neutron scatteringLight scatteringCondensed Matter::Soft Condensed Mattersymbols.namesakeOpticsDynamic light scatteringsymbolsScattering theoryRayleigh scatteringBiological small-angle scatteringbusinessPhysical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics
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Observation of Oriented Close-Packed Lattice Planes in Polycrystalline Hard-Sphere Solids.

1998

We report time-resolved Bragg scattering experiments on solidifying colloidal suspensions of hard spheres. The polar angle-averaged, integrated intensity of the (111) and (311) reflections show a transient, two-step behavior below melting, which depends in a complex way on the volume fraction and is not present for (200) or (220). Detailed analysis of the full two-dimensional scattering pattern reveals intensity maxima of sixfold symmetry close to the position of the (111) and (311) Debye-Scherrer rings. These can be explained assuming oriented crystals with close-packed planes parallel to the container walls. We show that the observed temporal behavior is due to competing homogeneous and h…

Materials scienceCondensed matter physicsScatteringbusiness.industryNucleationBragg's lawHard spheresLight scatteringSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsBiomaterialsColloid and Surface ChemistryOpticsLattice (order)Volume fractionCrystallitebusinessJournal of colloid and interface science
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Solidification kinetics of hard-sphere colloidal suspensions

2007

We investigate the solidification dynamics of hard-sphere colloidal suspensions applying simultaneously small-angle and Bragg light scattering. These experiments allow a consistent picture of nucleation and crystal growth on the level of large-scale density fluctuations and of density fluctuations on the level of individual crystallites. We observe a temporally almost constant nucleation rate after an induction time that decreases with supersaturation. The classical expectation for the nucleation rate density as a function of supersaturation is in accordance with our data. We investigate the validity of the Wilson—Frenkel growth law for hard-sphere systems, which also fits our data satisfac…

SupersaturationOrders of magnitude (time)ChemistryChemical physicsNucleationMineralogyCrystal growthCrystalliteHard spheresLight scatteringOrder of magnitude
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