Nano-particles play an important role in astrophysics (e.g. interstellar and intergalactic dust clouds) but in
medicine too ("Trojan horses" for transport of active substances into the organism), in chemistry (catalysis) and within many other ranges of
technology (e.g. production of new materials). Plasmas in reactive gases are successfully used, in order to produce nano-particles with
controlled characteristics. For astrophysical questions the optical characteristics of nano-particles and their dependence on size
distribution, composition and form are of special interest for a comparison with observations. Such questions are the center of this subproject.
The mechanisms that determine particle growth are unknown to a large extent - they are a further central investigation article.
Nano-particle with systematically changed composition (C-H, C-Si-H, C-Si-O-H, etc..) and morphology (e.g. "fluffy particles") shall be
produced in RF-plasmas from reactive gases and be examined regarding their formation kinetics, structure and optical characteristics. The physical
and chemical variables (gas composition, pressure, power, presence of large quantities of neutral radicals, UV radiation
portion) are to be varied systematically. Because of its close relation to astrophysics special attention is dedicated to the optical
characteristics in the close infrared range.
The question, how the IR-signatures change, if particles are exposed e.g. to a significant flux of atomic hydrogen, is also of importance.
Since a short while in situ diagnostics of these particles in plasma with multi-pass fourier-transform-infrared-absorptionspectroscopy
(FTIR) and Mie-ellipsometry is possible. This permits it to pursue directly the change of the signatures with progressive growth for the first time.
The dynamics of the early precursorphase and its chemical conversion is diagnostically opened by simultaneous use of
plasma-ion-mass-spectrometry. The characterisation of the particles is supplemented by ex-situ diagnostics of selected samples.
A goal of this project is the systematic production of nano-particles of different composition and size in reactive RF-stimulated
plasmas. Their properties are to be characterized and their signatures are to be compared with observations in astrophysics,
that can be led back to very large molecules or particles. Thus the interpretation of the astronomical observations is to be supported. The
center of interest are the optical signatures of the produced particles, in particular in the close infrared range. By the usage of
efficient, partly new in-situ diagnostics we expect here a clear progress in relation to the present state of research.
A second, equally important goal is the further clearing-up and an improved understanding of the complex growth mechanisms of
particles in plasmas. The new diagnostics takes here a key position, whose efforts are supported by accompanied modelling.