The U-shaped DC arc with aerosol supply was applied for the determination of Fe, Hg, Mn, and Pb in poplar (Populus alba L.) tree-rings.
(Author, shortened by G.Q.)ĭetermination of Fe, Hg, Mn, and Pb in three-rings of poplar (Populus alba L.) by U-shaped DC arc The existence of the resonance acceptor state in HgTe was proved by optical transmission measurements. The influence of clustering in the mixed crystal HgMnTe on the phonon spectra must be taken into account for Mn concentrations > 20%. Kramers-Kronig-data were in agreement with the theoretical results of the Barker-Verleur-model. Zero field splitting appears in PbMnTe in the valence band and indicates a weak ferromagnetism already observed in other measurements cited in the literature. To evaluate the data an oscillator fit was applied to cyclotron absorption (Faraday- and Voigt-configuration) and was proved to be in agreement with the experimental data. The extrapolation in the fan-charts to zero-magnetic field suggests residual spin splitting either in the conduction and/or in the valence band. The substitution of Mn-ions in the IV-VI-compound PbTe leads to semimagnetic effects resolved by magneto-reflectivity measurements. The model of Barker and Verleur (including clustering) was applied. The mixed crystal exhibits additional structures in the phonon spectrum. By alloying Mn-ions into the inverted gap- HgTe-crystal the band gap can be tuned to an open gap band structure. The investigated sample was n- HgTe, for which a resonant acceptor absorption in the conduction band was predicted. This technique was adapted for measurements on small gap semiconductors.
The so-called dual beam spectrometer consists of two coupled interferometers. International Nuclear Information System (INIS)Ī special method was developed in the framework of this thesis to solve the inherent problem of dynamic range in Fourier spectrometry by using optical compensation. Investigations of small-gap semiconductors: HgTe, HgMnTe and PbMnTe in the far infrared region using Fourierspectroscopic methods
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