Berlin 2014 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 23: Poster: Atomic clusters (with MO)
A 23.6: Poster
Dienstag, 18. März 2014, 16:30–18:30, Spree-Palais
Porosity and surface roughness of free SiO2 nanoparticlesl studied by wide angle X-ray scattering — •Burkhard Langer1, Christian Goroncy1, Christopher Raschpichler1, Thoralf Lischke2, Bernhard Wassermann1, Christina Graf1, and Eckart Rühl1 — 1Physikalische Chemie, Freie Universität Berlin — 2Max-Planck-Institut für Mikrostrukturphysik, Halle
Silica nanoparticles which consist of an amorphous network of SiO2 containing pores in the nanometer range (1-10) nm are used as a model system to study their porosity and roughness by wide angle X-ray scattering. The particles are prepared with a porous layer of an adjustable thickness between 5 and 50 nm. Dispersions of such nanoparticles are evaporated into a continuous aerodynamically focused free nanoparticle beam crossing a synchrotron radiation beam from BESSY II. The scattered X-ray intensity is detected over a wide angle range by an MCP detector which can be rotated between 10∘ and 170∘ around the interaction region [1]. Comparison of the X-ray scattering intensities with model calculations provides novel information on the surface roughness, porosity, and possible contributions of solvent in the pores.
While the angle dependent X-ray scattering intensity of nanoparticles with a smooth surface follows clearly the (qR)−4 power law given by Mie theory, nanoparticles with a rough surface and core-shell nanoparticles show a different behavior. Deviations from the pure Mie theory will be discussed in terms of the surface roughness compared to the incident X-ray wavelength.
H. Bresch et al., Faraday Discussions, 137, 389 (2008).