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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 18 (1996), S. 231-235 
    ISSN: 0392-6737
    Keywords: Mössbauer spectra ; Structure, bonding, conformation, configuration and isomerism of biomolecules ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Using the possibility to produce61Co sources at the MAinz MIcrotron,61Ni Mössbauer spectroscopy was applied to different kinds of chemical problems. Measurements of isomer shifts andV zz values in some common compounds and compounds with unusual chemical bonding for comparison with band structure calculations, measurement of61Ni Mössbauer parameters in model compounds for hydrogenase and dehydrogenase with an active [NiS4] centre, and study of novel binary NiF3 compounds at helium temperature are presented.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0630
    Keywords: 78.40 ; 71.25P ; 61.55M
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract X-ray and neutron diffraction experiments and optical studies were done on several alloys of the quasibinary series Li2Ag2−x In x , Li2Cd2−x In x , and Li2Zn2−x Cd x . Within a wide region the alloys crystallize homogenous in an NaTl-type structure (1≦x≦1.5 for Li2Ag2−x In x ; 0.6≦x≦1 for Li2Cd2−x In x ; 1.2≦x≦1.6 for Li2Zn2−x Cd x ). Most of the alloys investigated are colored and the color changes continuously as a function ofx. Measurements of the reflectivityr and the dielectric constants (ɛ1 and ɛ2) were done in the energy range 1.5 eV≦E≦3.3 eV by the method of elliptical analysis. In this energy range the curvesr(E) have minima which shift with increasingx to lower energy values. Calculations of the energy bands of LiAg, LiIn, LiCd, and Li2AgIn on the basis of the augmented plane wave method and the determination of the joint density show that the optical data can be interpretated on the assumption of interband transitions between the valence and the conduction bands and of transitions between the 4d-bands of silver and the energy states at the Fermi level.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 93 (1996), S. 177-189 
    ISSN: 1432-2234
    Keywords: Crystal potential ; Dynamic polarizability ; Absorption oscillator strength ; Halogen anion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We combine a time-dependent approach with a crystal potential model to study environment-specific optical linear response of closed-shell ions within crystals under the influence of an external time-varying field. It is shown how the dynamic dipole polarizability of free halogen anions within the normal dispersion region is altered due to the crystal potentials felt by the anions in environments appropriate for different binary cubic ionic lattices. The pole-positions of the in-crystal anion polarizability are found to be consistent with the vacuum ultraviolet absorption edges of the corresponding alkali halides and to vary linearly with the lattice potentials at the anion sites in these salts. It is observed that the crystal potential induces quite a large enhancement in the anionic absorption oscillator strengths of these dipole transitions, thereby making these values conform well with those of the first excitonic absorptions in such crystals.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 7 (1981), S. 169-176 
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The electric field gradient (EFG) in Mg2SiO4 is calculated on the basis of the extended point ion model, including the local term of the overlap contribution. The agreement with experimental data deduced from the quadrupole coupling constants and principal axes at the Mg sites is quite good. The results of the present calculation exhibit a small overlap contribution to the EFG at M1 and a clearly bigger one at M2, whereas the lattice contribution to the EFG at M1 and M2 is reversed. The distinct overlap effects are assumed to be due to the particular Mg2SiO4 crystal structure and the different point symmetry at M1 and M2. The oxygen polarizability and charge used to calculate the EFG tensor were found to be smaller than the theoretical polarizability and formal charge, respectively. The sign of the Mg quadrupole coupling constants at M1 and M2, which has not been determined experimentally, results from the EFG calculation as positive.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretica chimica acta 93 (1996), S. 177-189 
    ISSN: 0040-5744
    Keywords: Key words: Crystal potential ; Dynamic polarizability ; Absorption oscillator strength ; Halogen anion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  We combine a time-dependent approach with a crystal potential model to study environment-specific optical linear response of closed-shell ions within crystals under the influence of an external time-varying field. It is shown how the dynamic dipole polarizability of free halogen anions within the normal dispersion region is altered due to the crystal potentials felt by the anions in environments appropriate for different binary cubic ionic lattices. The pole-positions of the in-crystal anion polarizability are found to be consistent with the vacuum ultraviolet absorption edges of the corresponding alkali halides and to vary linearly with the lattice potentials at the anion sites in these salts. It is observed that the crystal potential induces quite a large enhancement in the anionic absorption oscillator strengths of these dipole transitions, thereby making these values conform well with those of the first excitonic absorptions in such crystals.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 15 (1993), S. 105-115 
    ISSN: 1573-739X
    Keywords: Calcium phosphates ; Drug compounding ; Excipients ; Particle size ; Physics ; Powders ; Tablets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ten commercially available calcium phosphates used for direct tableting were evaluated. The particle size distributions, powder properties, Sorption isotherms and pH values of aqueous slurries were compared. All samples showed good or at least sufficient flowability. Scanning electron micrographs illustrated the different kinds of manufacturing and gave hints on their expectable behaviour under compaction pressure. The sorption isotherms of identical chemical substances, which had been manufactured by different methods, differed strongly. This can be related to their specific surface areas. Most of the hydroxylapatites have large surface areas and can absorb up to more than 15% water at 93% relative humidity. Dibasic calcium phosphate dihydrate was non-hygroscopic and absorbed less than 1% water. With the exception of monobasic calcium phosphate monohydrate all calcium phosphates behaved quite neutral in water. Monobasic calcium phosphate monohydrate can be regarded as a solid acid. Although the calcium phosphates are usually stable substances, the role of crystal water in the case of dibasic calcium phosphate dihydrate and monobasic calcium phosphate monohydrate is problematic due to possible interactions with active ingredients.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 26 (1980), S. 317-319 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 26 (1980), S. 314-317 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 32 (1986), S. 619-624 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Through first-principles investigations on a number of models for anomalous muonium in diamond using the Unrestricted Hartree-Fock Cluster procedure, it is demonstrated that a muonium trapped near a double-positively charged vacancy is the most viable model for this center. This model is shown to successfully explain all the observed features of the hyperfine tensors A⇉ in diamond, silicon and germanium, namely, oblateness, opposite signs of A│ and A┼ in diamond and same signs for silicon and germanium, the trend in the strengths of the hyperfine tensors from diamond to germanium and the negative sign for A┼ in diamond.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 30 (1986), S. 253-264 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract First calculations of the Sternheimer charge perturbed antishieldingfunction β(r) within the uncoupled Hartree-Fock theory are reported for the He, Ne, Ar, Kr, and Xe isoelectronic series, respectively. The results should complement the previously reported calculations of the dual moment perturbed antishieldingfunction γ(r) [Hyp. Int. 12(1982)113; 14(1983)243] and would facilitate more complete calculations of the as yet to be fully evaluated theory of electric field gradients in metals based on the energy of interaction approach. The general trends in β(r) are pointed out and explained.
    Type of Medium: Electronic Resource
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