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P: Plasmaphysik

P 2: Plasma Technology, Diagnostics I

P 2.3: Vortrag

Montag, 2. April 2001, 17:00–17:15, 2032

Study of the melting of particles in reactive plasmas by Mie-ellipsometry — •Gerd Gebauer and Jörg Winter — Ruhr-Universität Bochum

Plasma generated nanoparticles play an important role in modern materials technology, in catalysis and, for instance, in astrophysics. Plasma assisted deposition of thin films consisting of an amorphous matrix into which well controlled and characterized nanoparticles are embedded (dispersion coatings) may lead the way to new materials with designed properties depending on the amount of the crystalline phase.

This study aims at the elaboration of a diagnostic method (Mie Ellipsometry) for the insitu characterization of particles which may originate from the coagulation of macromolecules in reactive plasmas or which may be intruduced from the outside into the plasma. The polarisation state of the scattered light is measured for a fixed scattering angle (ellipsometry) and is analyzed on the basis of Mie theory. The application of Mie-ellipsometry delivers the mean particle diameter, the refraction constant and the size distribution of the particles. Our systems operates at three wavelengths simultaneously, reducing the multivalency inherent to Mie scattering. The minimum size which can be measured with our arrangement is about 40 nm, at the moment. The technique will presented and discussed at the example of the in situ surface modification of methylmelamine-formaldehyde particles in reactive plasmas and at the growth of carbonaceous particles from hydrocarbon plasmas.