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HL: Fachverband Halbleiterphysik
HL 32: Quantum dots and wires: preparation and characterization I
HL 32.2: Vortrag
Mittwoch, 27. Februar 2008, 14:30–14:45, ER 270
Nanoparticle size separation in a drying fluid droplet — •Matthias Offer1, Cedrik Meier1, Stephan Lüttjohann1, Axel Lorke1, and Hartmut Wiggers2 — 1Experimental Physics, Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany — 2Institute of Combustion and Gas Dynamics, Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany
We study the deposition of optically active nanoparticles with a broad size distribution in a drying fluid droplet on a solid surface. The nanoparticles are dispersed in a drying droplet and migrate to the edge of the droplet to form ring-like structures on the surface. After deposition we find a particle size separation, i.e., different particle diameters are deposited in different spatial locations. This leads to a position-dependent energy shift in the micro-photoluminescence signal. Furthermore, the observed photoluminescence peak of the deposited nanoparticles has a significantly lower full width at half maximum (FWHM) than the nanoparticle powder used for dispersion. The spatial size separation is caused by an outward flow within the droplet. The flow is driven by the loss of solvent during the evaporation phase. Nanoparticles with small masses are more stable in the dispersion than particles with large masses. There fore large particles are deposited first. We compare the deposition results for silicon nanoparticles, which are synthesized from the gas-phase, to results obtained using commercially available PbS nanoparticles with functionalized surfaces.