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- Meletov, Kostas P., et al.
(författare)
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Pressure-induced transformations and optical properties of the 2D-tetragonal polymer of C60 at pressures up to 30 GPa.
- 2002
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Ingår i: Journal of Experimental and Theoretical Physics. - : American Institute of Physics. - 1063-7761 .- 1090-6509. ; 95:4, s. 736-747
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Tidskriftsartikel (refereegranskat)abstract
- The Raman spectra of the two-dimensional tetragonal (2D(T)) polymeric phase of C60 have been studied in situ at pressures up to 30 GPa and room temperature. The pressure dependence of the phonon modes shows an irreversible transformation of the material near 20 GPa into a new phase, most probably associated with the covalent bonding between the 2D polymeric sheets. The Raman spectrum of the high-pressure phase is intense and well resolved, and the majority of modes are related to the fullerene molecular cage. The sample recovered at ambient conditions is in a metastable phase and transforms violently under laser irradiation: the transformed material contains mainly dimers and monomers of C60 and small inclusions of the diamond-like carbon phase. The photoluminescence spectra of the 2D(T) polymer of C60 were measured at room temperature and pressure up to 4 GPa. The intensity distribution and the pressure-induced shift of the photoluminescence spectrum drastically differ from those of the C60 monomer. The deformation potential and the Grüneisen parameters of the 2D(T) polymeric phase of C60 have been determined and compared with those of the pristine material.
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| 2. |
- Odnoblyudov, MA, et al.
(författare)
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Resonant acceptor states in uniaxially strained semiconductors
- 2002
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Ingår i: Journal of Experimental and Theoretical Physics. - : Pleiades Publishing Ltd. - 1063-7761 .- 1090-6509. ; 94:3, s. 593-602
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Tidskriftsartikel (refereegranskat)abstract
- A new approach to calculating the parameters of resonant states is proposed, which also makes it possible to determine the probabilities of the resonant scattering and capture probabilities at the resonant state. This approach is based on the application of the method of configuration interaction, which was proposed for the first time by Fano for an analysis of field ionization of the helium atom. Following Fano, use is made of two different Hamiltonians of the initial approximation for the states of continuum and the initial local state. Following Dirac, the wave functions are constructed in the same way as in the general theory of scattering. A detailed analysis and specific calculations are made for resonant acceptor states in uniaxially strained germanium under a pressure directed along the [001] and [111] axes. (C) 2002 MAIK "Nauka/Interperiodica".
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