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  • Inorganic Chemistry  (14)
  • 36.40  (3)
  • 14.80.Pb  (2)
  • Transition metals  (2)
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  • 1
    ISSN: 1434-601X
    Schlagwort(e): 14.80.Pb ; 13.10. + q ; 12.20.Fv
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Motivated by the observation of energy- and momentum-correlatede + e − pairs in heavy ion collisions, a search for resonances ine + e − scattering at the corresponding energies has been made. Thee + e − decay channel is analyzed in a time window from ∼ 10−13 s to ∼ 10−11 s with a set-up optimized for low-background detection of delayede + e − decays. The two-photon decay channel of a hypothetical resonance is investigated by measuring the two-photon annihilation-in-flight excitation function. New upper limits for the partiale + e − decay width Γee of a few meV are derived for total centre-of-mass energies √s between 1.78 and 1.92 MeV, taking into account the dilepton as well as the two-photon decay of a neutral resonance.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 77 (1990), S. 123-141 
    ISSN: 1432-2234
    Schlagwort(e): Pseudopotentials ; Spin-orbit operator ; Transition metals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Nonrelativistic and quasirelativisticab initio pseudopotentials substituting the M(Z−28)+-core orbitals of the second row transition elements and the M(Z−60)+-core orbitals of the third row transition elements, respectively, and optimized (8s7p6d)/[6s5p3d]-GTO valence basis sets for use in molecular calculations have been generated. Additionally, corresponding spin-orbit operators have also been derived. Atomic excitation and ionization energies from numerical HF as well as from SCF pseudopotential calculations using the derived basis sets differ in most cases by less than 0.1 eV from corresponding numerical all-electron results. Spin-orbit splittings for lowlying states are in reasonable agreement with corresponding all-electron Dirac-Fock (DF) results.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2234
    Schlagwort(e): Pseudopotentials ; Transition metals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Recently published nonrelativistic and quasirelativistic energy-adjustedab initio pseudopotentials representing the M(Z−28)+ cores of the second row transition metal atoms and the M(Z−60)+ cores of the third row transition metal atoms have been tested in SCF, CI(SD) and CEPA1 calculations of the spectroscopic constants (R e ,D e , and ω e ) of the ground states of the neutral and singly charged silver and gold dimers, and in state averaged CASSCF and multi-reference CI(SD) calculations of the spectroscopic constants (R e ,D e , ω e , μ e , ∂μ/∂R). Comparison is made with experimental and reliable theoretical data where available; in the case of the hydrides, additional calculations with pseudopotentials published by other groups have been made for comparison.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1434-601X
    Schlagwort(e): 13.10.+q ; 12.20.Fv ; 14.80.Pb
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A monoenergetic positron (e +) beam (ΔT/T〈5·10−4) from the Stuttgart pelletron accelerator and a 4.6 mg/cm2 Be target has been employed to investigatee + e −scattering in the MeV region in a large solid angle with high statistics by means of a novel positionsensitive detector system. Superimposed on the Bhabha scattering, a structure has been found at ane + kinetic energy of 2263 keV (810 keV excitation energy in thee + e −rest frame). From the energy-integrated resonance cross-section of $$\sigma _{res} \cdot \Gamma _{res}^{e^ + e^ - } $$ ≅30 b·eV (c.m.) and the standard resonance cross-section we estimate partial resonance widths $$\Gamma _{res}^{e^ + e^ - } $$ ≅72 meV or 24 meV for total angular momenta J=0 or J=1, respectively. The structure, which has not been predicted within the framework of quantum electrodynamics, coincides with one of the sum energies of the correlatede + e −lines observed in heavy-ion collisions.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 15 (1990), S. 79-86 
    ISSN: 1434-6079
    Schlagwort(e): 31.20 ; 36.40 ; 82.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The alternating process of adsorption of Ag+ and trapping of a photoelectron on a (100) AgBr surface is investigated by quantum chemical calculations. The results give some insight into the initial steps of the photographic process (absorption of two photons which lead to the formation of a sublatent image).
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 6 (1987), S. 193-198 
    ISSN: 1434-6079
    Schlagwort(e): 31.15 ; 36.40 ; 82.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Having studied free silver clusters by quantum chemical calculations we now present a method to take into account the influence of a silver halide surface on adsorbed silver clusters. The model for the surface will be a silver halide cluster as frozen crystal section. The interactions are discussed in detail; a new bromide pseudopotential may be of special interest. Results with this method will be given in subsequent papers.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 6 (1987), S. 287-292 
    ISSN: 1434-6079
    Schlagwort(e): 31.20 ; 36.40 ; 82.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The adsorption of Ag+ and Ag on a (100) AgBr surface is investigated. Interstitial subsurface sites and incomplete surfaces (with ledges and kinks) are also considered. Equilibrium geometries, adsorption energies and ionization potentials have been calculated. Migration of neutral Ag on the surface and crystal growth of AgBr are discussed, and a comparison with other theoretical results is given.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 559 (1988), S. 17-26 
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: New Oxoaluminate KLi4[AlO4]Transparent and colourless single crystals of Kli4[AlO4] have been prepared for the first time by heating mixtures of Li5AlO4 and K2O in the ratio 1:5 [Ni-tube, 950°C, 50 d]. The structure determination [four-circle diffractometer, MoKα, 1699 of 2427 I0 (hkl), R = 7.41%, Rw = 4.3%] proves the monoclinic space group P21/c with a = 554.4(3), b = 1544.1(7), c = 1103.3(6) pm, β = 109.71(5)°, parameters see text. Characterizing are “isolated” AlO4 groups with symmetry nearly Td. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, have been calculated.
    Notizen: Erstmals wurde KLi4[AlO4] durch Erhitzen innig verriebener Gemenge von Li5AlO4 und K2O im molaren Verhältnis 1:5 [Ni-Bömbchen, 950°C, 50 d] dargestellt. Wir erhielten farblose monokline Einkristalle (P21/c) mit a = 554,4(3), b = 1544,1(7), c = 1103,3(6) pm, β = 109,71(5)°.Die Struktur wurde mittels Vierkreisdiffraktometerdaten [MoKα, 1699 von 2427 I0(hkl), R = 7,41%, Rw = 4,3%] bestimmt, Parameter siehe Text. Charakteristisch sind “isolierte” AlO4-Gruppen, Symmetrie nahezu Td. Der Madelunganteil der Gitterenergie, MAPLE, und Effektive Koordinationszahlen, ECoN, diese über Mittlere Fiktive Ionenradien, MEFIR, wurden berechnet.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 564 (1988), S. 45-60 
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Novel Oxoplumbates(II) with Isolated Anion Structure: Rb4[PbO3] and Cs4 [PbO3]For the first time Rb4[PbO3] have been prepared as single crystals. The structure determination (four-circle diffractometer data) [Rb4[PbO3]: 1818 I0 (hkl), MoKα, R = 6.49%, Rw = 6.83%, space group Pbca (a = 681.2(1), b = 1178.7(1), c = 1979,9(1) pm), Z = 8; Cs4[PbO3]: 3663 Io (hkl), AgKα, R = 11.35%, Rw = 9.82%, space group P21 (a = 1188.1(2), b = 734.4(1), c = 1176.2(2) pm, β = 111.52(2)°), Z = 4] proves in both cases the expected “isolated” [PbO3] groups. Comparing the oxides the arrangements of these groups shows surprising differences (see text). The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, have been calculated.
    Notizen: Erstmals dargestellt wurden Rb4[PbO3] und Cs4[PbO3] in Form von Einkristallen. Nach der Strukturbestimmung mit Vierkreisdiffraktometerdaten [Rb4[PbO3]: 1818 I0 (hkl), Mokα, R = 6,49%, Rw = 6,83%, Raumgruppe Pbca (a = 681,2(1), b = 1178,7(1), c = 1979,9(1) pm), Z = 8; Cs4[PbO3]: 3663 Io (hkl), AgKα, R = 11,35%, Rw = 9,82%, Raumgruppe P21 (a = 1188,1(2), b = 734,4(1), c = 1176,2(2) pm, β = 111,52(2)°), Z = 4] liegen bei beiden Oxiden „isolierte“ [PbO3]-Gruppen von, deren Anordnung zueinander sich jedoch grundsätzlich unterscheidet, (Einzelheiten vgl. Text). Der Madelunganteil der Gitterenergie, MAPLE, und Effektive Koordinationszahlen, ECoN, werden angegeben.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 548 (1987), S. 165-174 
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: On Oxoplumbates(IV): Ba2PbO4For the first time single crystals of Ba2PbO4 have been prepared by exchange reaction [BaPbO3: Li2O2 = 2:4; Ag-cylinder, Argon, quartz ampoule, 800°C, 30 d]. The structure determination [137 I0(hkl), fourcircle diffractometer PW 1100 (Fa. Philips), MoKα, R = 5.04%, Rw = 4.93%] confirms the space group I4/mmm with a = 430.08 and c = 1325.63 pm (K2NiF4-type, parameters s. text).
    Notizen: Erstmals in Form von Einkristallen wurde Ba2PbO4 durch Austauschreaktion [BaPbO3: Li2O2 = 2:4; Ag-Bömbchen, Argon, Quarzampulle, 800°C, 30 d] dargestellt. Die Strukturaufklärung [137 I0(hkl), Vierkreisdiffraktometer PW 1100 (Fa. Philips), MoKα, R = 5,04%, Rw = 4,93%] belegt die Raumgruppe I4/mmm mit a = 430,08 und c = 1325,63 pm (K2NiF4-Typ, Parameter s. Text).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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