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- Paskova, T., et al.
(författare)
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6H-SiC crystallinity behaviour upon B implantation studied by Raman scattering
- 1998
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Ingår i: Silicon carbide, III-nitrides and related materials : ICSCIII-N'97. - : Trans Tech Publications Inc.. - 0878497900 ; , s. 741-744
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Konferensbidrag (refereegranskat)abstract
- In this study, B ion implantation was performed in n-type 6H-SiC single crystals at 500 degrees C. The implanted specimens were annealed at 1700 degrees C in SiH4 atmosphere. Lattice damage induced by implantation and its recovery was characterised by Raman scattering. Reduced damage compared with other ions implantation was observed. Recrystallization of the implanted material and absence of amorphous phases was detected after high temperature annealing.
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| 8. |
- Ivanov, Alexander V., et al.
(författare)
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Bis(diethyldithiocarbamato)pyridinezinc(II) and -copper(II) clathrates M(Edtc)2Py·nL (L = CH2Cl2 and CHCl3; n = 1 and 0.5) : Molecular and crystal structures and EPR and high-resolution solid-state (13C, 15N) NMR spectra
- 1999
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 25:8, s. 543-555
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Tidskriftsartikel (refereegranskat)abstract
- X-ray diffraction analysis, EPR, and high-resolution solid-state (13C, 15N) NMR spectroscopy were used to examine structural organization and spectral properties of six bis(diethyldithiocarbamato)pyridine-zinc(II) and copper(II) solvates with dichloromethane and chloroform, M(Edtc)2Py·nL (n = 1 and 0.5). Typical of the clathrate-type structures, the compounds are penetrated by the ordered molecular channels filled with chemically nonbonded chlorohydrocarbon molecules. At the molecular level, the geometry of coordination polyhedra of complexing atoms is intermediate between trigonal bipyramidal and square pyramidal (the contribution of the square-pyramidal component is quantitatively estimated for the zinc clathrate). Accordingly, the ground state of the unpaired electron in the copper(II) compounds is a combination of the dx2-y2 and dz2 orbitals. It is shown that the nonequivalence of the Edtc- ligands in zinc(II) clathrates manifests itself both magnetically and structurally. The chlorine atoms of the solvate dichloromethane molecules, unlike chloroform molecules, are disordered over the two structural positions with different multiplicities. The 13C and 15N NMR signals are assigned to the atomic positions in the resolved molecular structures
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| 9. |
- Ivanov, Alexander V., et al.
(författare)
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Bis(diethyldithiocarbamato)pyridinezinc(II) and copper(II) clathrates with pyridine: Molecular structure and EPR and high-resolution solid-state (13C, 15N) NMR spectra
- 1998
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 24:9, s. 645-654
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Tidskriftsartikel (refereegranskat)abstract
- EPR, high-resolution solid-state (13C, 15N) NMR, and X-ray diffraction methods were used to study bis(diethyldithiocarbamato)pyridinezinc(II) and copper(II) clathrates with pyridine, M(EdIc)2Py · Py. The structural functionalities of the Py molecules in these clathrates were found to be different: one of them is coordinated to the complexing atom, while the other (solvate) is hydrogen-bonded to the sulfur atom of one of the ligands. The heterocycle of the uncoordinated Py molecule was found to be geometrically distorted. The structures of the copper and zinc coordination polyhedra are close to trigonal-bipyramidal: two sulfur atoms and the nitrogen atom of pyridine form the equatorial plane; another two sulfur atoms occupy axial positions at larger distances. EPR spectra of the magnetically diluted copper(II) clathrate exhibit well-resolved SHFS from the nitrogen atom of Py, owing to the contribution of the dz2 orbital to the ground-state wave function of the unpaired electron. The NMR data suggest that the nitrogen atoms of the Edtc- ligands are magnetically inequivalent and that the 15N chemical shift of the uncoordinated Py molecule changes in an unusual fashion. Signal assignment was carried out for the experimental 13C and 15N NMR spectra
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| 10. |
- Ivanov, Alexander V., et al.
(författare)
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Rotation isomers of bis(diethyldithiocarbamato)zinc(II) adduct with pyridine, Zn(EDtc)(2)center dot Py: ESR, C-13 and N-15 CP/MAS NMR and single-crystal X-ray diffraction studies
- 1999
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Ingår i: Polyhedron. - 0277-5387 .- 1873-3719. ; 18:15, s. 2069-2078
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Tidskriftsartikel (refereegranskat)abstract
- The adduct of bis(diethyldithiocarbamato)zinc(II) with pyridine, Zn(EDtc)2·Py, was prepared and studied by means of ESR (63Cu2+ and 65Cu2+ were used as spin labels), solid-state natural abundance 13C and 15N CP/MAS NMR spectroscopy and single-crystal X-ray diffraction data analysis. Two rotation isomers of the adduct were unambiguously determined by these three independent methods. It was found that these two isomers have different orientations of the pyridine ring about the N(Py)-Zn axis. The acute angles of the plane of the pyridine molecules relative to the most weak Zn-S bond are equal to 45.6 and 52.7° in the different isomers. Adduct molecules adopt a geometry which is intermediate between the square pyramidal (C4v) and the trigonal bipyramidal (D3h). All ESR and NMR resonances of Zn(EDtc)2·Py were assigned
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