Journal Article10.1002/PPSC.200700004
Dynamic Light Scattering for the Characterization of Polydisperse Fractal Systems: I. Simulation of the Diffusional Behavior
Uwe Kätzel,Rainer Bedrich,Michael Stintz,R. Ketzmerick,Torsten Gottschalk-Gaudig,Herbert Barthel +5 more
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TL;DR: In this paper, an algorithm is developed that enables the generation of aggregates with a tunable fractal dimension and an arbitrary number of primary particles, which is of great relevance for the interpretation of DLS results.
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Abstract: Dynamic light scattering (DLS) is a method used to size nanoscale and submicron particles by measuring their thermal motion (diffusion) in a liquid environment. The measured diffusion coefficients are related to the hydrodynamic particle size via the Stokes-Einstein equation. This paper addresses the application of DLS for the characterization of diluted suspensions of pyrogenic silica, which consist of polydisperse fractal-like aggregates composed of sintered spherical primary particles. Simulations are employed to establish a relationship between the structural properties of the aggregates and their diffusional behavior. Therefore, an algorithm is developed that enables the generation of aggregates with a tunable fractal dimension and an arbitrary number of primary particles. The results provide evidence that the hydrodynamic radii show a different scaling compared to the structural radius of gyration, which is of great relevance for the interpretation of DLS results. In addition, the influence of rotational diffusion has to be accounted for in the measurements.
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Citations
Formation of Pyrogenic Silica: Spectroscopic and Quantum Chemical Insight
TL;DR: In this paper, the genesis of amorphous silica under high-heat conditions from SiO2 molecules through protoparticles, primary particles, and aggregates to agglomerates using vibrational spectra and quantum chemical simulations data.
The Mobility of Fractal Aggregates: A Review
TL;DR: A review of the experimental and theoretical literature describing the mobility of fractal aggregates over the previous three decades is presented in this article, where the entire Knudsen number range from continuum to free molecular is reviewed.
Evidence of structural reorganization during aggregation of silica nanoparticles
TL;DR: In this paper, an optical model has been developed to extract both fractal dimension Df and primary particle radius rpp of the formed aggregates from these data, which clearly indicate a densification of the clusters as aggregation proceeds.
Overestimation of the fractal dimension from projections of soot agglomerates
TL;DR: In this paper, an algorithm is proposed to generate 3D synthetic agglomerates that mimic the fractal geometry of real ones, and the real 3D radius of gyration is measured and compared to the one found from projections.
•Dissertation
Ice nucleation by combustion products at conditions relevant to mixed-phase clouds
Nsikanabasi Silas Umo
- 01 May 2014
TL;DR: In this article, the authors investigated the ice nucleation abilities of soot and combustion ashes in the immersion mode at conditions relevant to mixed-phase clouds and found that combustion ashes can account for global primary ice nuclei number up to 1 cm-3, and this could impact on primary ice formation budget in mixed phase clouds.
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