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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 296 (1980), S. 55-63 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In order to describe dissipative heavy ion collisions microscopically a generalized master equation for the reduced density operator of the relative motion is derived. In the approach phase the description of the time development of the internal system is considerably simplified by employing a doorway concept. Concerning the coupling between doorway and more complex states a strong and weak coupling limit is defined. The resulting classical equation for the relative motion shows up to be reversible at the beginning of the collision process and becomes irreversible later on. The corresponding friction coefficient tourns out to be proportional to the width of the doorway states.
    Type of Medium: Electronic Resource
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 314 (1983), S. 97-106 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A consistent treatment of the relative and intrinsic motion which goes beyond the mean-field approach allows to include the fluctuations of the time-dependent mean field for the intrinsic as well as for the relative motion. Starting with the v. Neumann equation for the total density matrix, we derive a modified equation for the intrinsic many-body density matrix. This equation is used to obtain the quantum kinetic equations for the one-body density matrix and the two-body correlator. In the time-dependent single-particle basis, the occupation numbers change in time due to a collision term originating from residual two-body interactions which account for equilibration, and due to the fluctuations of the external mean field. The relations to TDHF with collision term are discussed. Special attention is paid to the conditions for a diabatic evolution of the single-particle states and to finite size effects which play an important role to make two-body collisions operative in finite nuclei.
    Type of Medium: Electronic Resource
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 342 (1992), S. 161-167 
    ISSN: 1434-601X
    Keywords: 24.10.Cn ; 25.70.−z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a coupled set of equations for the one-body density matrix and the two-body correlation function consistent with trace relations and conservation laws which provide an extension of correlation dynamics on the two-body level. The additional interaction terms are discussed in the context of time-dependent G-matrix theory and NQCD and studied numerically by one-dimensional calculations for colliding finite fermion systems.
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  • 24
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 337 (1990), S. 175-183 
    ISSN: 1434-601X
    Keywords: 24.10.Cn ; 25.70.−z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamical description of strongly interacting finite Fermi systems is based on coupled equations of motion for the one-body density matrixρ(11′) and the two-body correlation functionc 2(12, 1′2′) as obtained from the density-matrix hierarchy. The truncation schemes considered exceed the conventional Brueckner-Hartree-Fock scheme and also apply for nonstationary problems. In the limit of slow processes in time the equation of motion for the two-body correlation functionc 2 can be integrated in time and closed expressions can be given for the dynamical evolution ofρ(11′). When performing a Wigner transformation and adopting semiclassical limits this gives a transport equation of the Uehling-Uhlenbeck type for the one-body phase-space distributionf(x,p;t). Furthermore, in the small amplitude limit, we obtain a set of coupled equations for particle-hole (p-h),2p-2p, 2h-2h, 2p-2h, 1p-3h, 1h-3p amplitudes beyond the level of second RPA which provide a genuine basis for the description of giant resonances and their damping width.
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  • 25
    ISSN: 0044-2313
    Keywords: P4Si ring systems ; NMR data, crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of the Silatetraphospholanes (tBuP)4SiMe2, (tBuP)4SiCl2, and (tBuP)4Si(Cl)SiCl3 Molecular and Crystal Structure of (tBuP)4SiCl2The reaction of the diphosphide K2[(tBuP)4] 7 with the halogenosilanes Me2SiCl2, SiCl4 or Si2Cl6 in a molar ratio of 1:1 leads via a [4 + 1]-cyclocondensation reaction to the silatetraphospholanes (tBuP)4SiMe2 1,1-dimethyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 1, (tBuP)4SiCl2, 1,1-dichloro-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 2, and (tBuP)4Si(Cl)SiCl3, 1-chloro-1-trichlorsilyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 3, respectively, with the 5-membered P4Si ring system. The reaction leading to 1 is accompanied with the formation of the by-product Me2(Cl)-Si-(tBuP)4-Si(Cl)Me2 1a (5:1), which has a chain structure. On warming to 100°C 1a decomposes to 1 and Me2SiCl2. The compounds 2 and 3 do not react further with an excess of 7 due to strong steric shielding of the ring Si atoms by the t-butyl groups. 1, 2 and 3 could be obtained in a pure form and characterized NMR spectroscopically; 2 was also characterized by a single crystal structure analysis. 1a was identified by NMR spectroscopy only.
    Notes: Bei der Reaktion zwischen dem Diphosphid K2[(tBuP)4] 7 und den Halogensilanen Me2SiCl2, SiCl4 bzw. Si2Cl6 im Molverhältnis 1:1 findet eine [4 + 1]-Cyclokondensationsreaktion statt, bei der die Silatetraphospholane (tBuP)4SiMe2, 1,1-Dimethyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholan, 1, (tBuP)4SiCl2, 1,1-Dichloro-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholan, 2, und (tBuP)4Si(Cl)SiCl3, 1-Chloro-1-trichlorsilyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholan, 3, mit dem binären P4Si-Fünfringgerüst gebildet werden. Bei der Synthese von 1 entsteht ferner das kettenförmige Nebenprodukt Me2(Cl)Si-(tBuP)4-Si(Cl)Me2 1a (5:1), das beim Erwärmen auf 100°C unter Bildung von 1 und Me2SiCl2 zerfällt. Die Verbindungen 2 und 3 reagieren nicht mit überschüssigem 7, was auf eine starke sterische Abschirmung der Ring-Si-Atome durch die benachbarten t-Butyl-Gruppen zurückzuführen ist. 1, 2 und 3 konnten in reiner Form isoliert und NMR-spektroskopisch charakterisiert werden; 1a konnte nur 31P-NMR-spektroskopisch identifiziert werden. Von 2 wurde eine Einkristallstrukturanalyse durchgeführt.
    Additional Material: 1 Ill.
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  • 26
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 901-904 
    ISSN: 0044-2313
    Keywords: Iron chlorides, lithium ; Mößbauer spectra ; neutron diffraction ; Suzuki type ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mößbauer and Neutron Diffraction Studies on Li6FeCl8On Suzuki-Type Li6FeCl8 Mößbauer spectra and neutron powder diffraction data are presented. The Suzuki-type structure (space group Fm3m, Z = 4, 1 031.11(1) pm) was supported refining by the Rietveld method (program PROFIL) to a final R1 = 6.8%. The Mößbauer spectra confirm the ideal octahedral coordination of the Fe2+ ions (no quadrupole splitting). The isomer shift of 1.097(1) mm s-1 at 295 K resembles those of other ferrous chlorides. At temperatures above the phase transition to deficient NaCl-type solid solution the half-width of the Mößbauer signal strongly increases.
    Notes: Die Mößbauer-Spektren und Neutronenpulver-Strukturdaten der Suzukiphase Li6FeCl8 werden mitgeteilt. Die Struktur (Raumgruppe Fm3m, Z = 4, a = 1 031,11(1) pm) konnte mit Hilfe des Rietveld-Verfahrens (Programm PROFIL) bis zu einem R-Wert R1 = 6,8% verfeinert werden. Die Mößbauer-Spektren ergeben eine exakt oktaedrische Umgebung von Fe2+ (keine Quadrupol-Aufspaltung). Die Isomerieverschiebung (1,097(1) mm s-1 bei 295 K) entspricht der anderer Eisen(II)chloride. Bei Temperaturen oberhalb der Phasenumwandlung zum defizienten NaCl-Typ-Mischkristall nimmt die Halbwertsbreite des Mößbauer-Signals zu.
    Additional Material: 1 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 993-998 
    ISSN: 0044-2313
    Keywords: Bromozincates ; zinc ; olivine-type halides ; neutron diffraction ; fast ionic conductivity ; Raman spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Halogenozincates M2IZnX4 (MI = Li, Na; X = Cl, Br) of Olivine TypeThe hitherto unknown tetrabromozincates Li2ZnBr4 and Na2ZnBr4 have been prepared. Quaternary halides Li2Zn(Cl, Br)4 and Li2Zn(Br, I)4 have been not obtained due to decomposition to mixtures of LiCl and ZnBr2, and LiBr and ZnI2. The crystal structures of the olivine-type bromides and of the high-temperature polymorph of Li2ZnCl4 have been determined by neutron powder diffraction using the Rietveld method (space group Pnma, Z = 4, a = 1 360.41(4), b = 788.47(2), c = 647.07(2) pm, RI = 9.07% (Li2ZnBr4), a = 1 446.32(5), b = 853.02(3), c = 676.61(2) pm, RI = 9.29% (Na2ZnBr4), a = 1 277.60(3), b = 741.76(2), c = 611.10(1) pm, RI = 7.63% (Li2ZnCl4)). The Raman spectra as well as the results of thermal analyses (DSC) and conductivity measurements (impedance spectroscopy) are presented and discussed. Contrary to Li2ZnCl4, Li2ZnBr4 and Na2ZnBr4 do not undergo any phase transition between 20°C and their melting points.
    Notes: Die Darstellung der bisher nicht bekannten Tetrabromozinkate Li2ZnBr4 und Na2ZnBr4 wird beschrieben. Quaternäre Halogenide des Typs Li2Zn(Cl, Br)4 bzw. Li2Zn(Br, I)4 konnten nicht erhalten werden. Es erfolgt Entmischung zu LiCl und ZnBr2 bzw. LiBr und ZnI2. Die Kristallstrukturen der im Olivintyp kristallisierenden Bromide und der Hochtemperaturform von Li2ZnCl4 wurden auf der Basis von Neutronenpulver-Messungen nach der Rietveld-Methode bestimmt (Raumgruppe Pnma, Z = 4, a = 1 360,41(4), b = 788,47(2), c = 647,07(2) pm, RI = 9,07% (Li2ZnBr4), a = 1 446,32(5), b = 853,02(3), c = 676,61(2) pm, RI = 9,29% (Na2ZnBr4), a = 1 277,60(3), b = 741,76(2), c = 611,10(1) pm, RI = 7,63% (Li2ZnCl4)). Raman-Spektren sowie das Ergebnis thermoanalytischer Untersuchungen (DSC) und Leitfähigkeitsmessungen (Impedanz-Spektroskopie) werden mitgeteilt. Li2ZnBr4 und Na2ZnBr4 zeigen im Gegensatz zu Li2ZnCl4 zwischen 20°C und dem Schmelzpunkt keine Phasenumwandlung.
    Additional Material: 5 Ill.
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  • 28
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 8-15 
    ISSN: 0044-2313
    Keywords: P3B and P4B ring systems ; NMR data ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure Analysis of (i-Pr)2NB(t-BuP)3 and (i-Pr)2NB(t-BuP)4The diphosphide K(t-Bu)P-(t-BuP)2-P(t-Bu)K obtained by the cleavage reaction of the 3-membered ring system (i-Pr)2BN(t-BuP)2 with potassium reacts with t-BuPCl2 at -78°C under ring expansion to form the P3B ring system (i-Pr)2NB(t-BuP)3 - 1,2,3-tri-t-butyl-tri-phospha-4-diisopropyl-aminoboretane (1). - The 5-membered P4B ring system (i-Pr)2NB(t-BuP)4 - 1,2,3,4-tetra-t-butyl-tetraphospha-5-diisopropylaminoborolidine, (2) - is formed from K(t-Bu)P—(t-BuP)2—P(t-Bu)K and (i-Pr)2NBCl2 analogous to the above reaction. 1 and 2 could be obtained in a pure form and characterized NMR spectroscopically and by X-ray structure analysis. 1 shows at 200 K two conformation isomers; for 2 31P-10,11B-isotopic shifts could be identified.
    Notes: Das bei der Spaltung des Dreiringes (i-Pr)2BN(t-BuP)2 mit Kalium gebildete Diphosphid K(t-Bu)P—BN(i-Pr)2—P(t-Bu)K reagiert bei -78°C mit t-BuPCl2 unter Ringerweiterung zu (i-Pr)2NB(t-BuP)3-1,2,3-Tri-t-butyl-triphospha-diisopropyl-aminoboretan, (1) - mit einem P3B-Ringgerüst. In analoger Weise entsteht bei der Reaktion zwischen K(t-Bu)P—(t-BuP) - (t-BuP)2—P(t-Bu)K und (i-Pr)2NBCl2 das P4B-Ringsystem (i-Pr)2NB(t-BuP)4 - 1,2,3,4-Tetra-t-butyl-tetraphospha-5-diiso-propylaminoborolidin, (2) -, 1 und 2 konnten in reiner Form isoliert, NMR-spektroskopisch und durch Röntgenstrukturanalysen charakterisiert werden. 1 zeigt bei 200 K zwei Konformationsisomere; bei 2 konnten 31P-10,11B-Isotopieverschiebungen nachgewiesen werden.
    Additional Material: 4 Ill.
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  • 29
    ISSN: 0044-2313
    Keywords: [Disodium(2 +)][1,2-Diselena-diboranate(2 -)] ; [Tetraphenylphosphonium(1 +)][μ2-Selena-(diboranyl)boranate(1 -)] ; preparation ; SCF calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Vibrational Spectroscopic Investigation of [H3B—Se—Se—BH3]2- and [H3B-μ2-Se(B2H5)]- Crystal Structure and Theoretical Investigation of the Molecular Structure of [H3B-μ2-Se(B2H5)]-M2[H3B—Se—Se—BH3] 1 is produced by the reaction between elemental selenium and MBH4 (1 : 1) in triglyme (diglyme), under dehydrogenation. 1 reacts with an excess of B2H6 to give M[H3B-μ2-Se(B2H5)] 2 which is also formed in the reaction of THF · BH3 with 1. These reactions proceed under cleavage of the Se—Se bond and hydrogen evolution. [(C6H5)4]Br reacts with Na · 2 to form [(C6H5)4P] · 2 which crystallizes in the tetragonal space group I4 (Nr. 82). An X-ray structure determination failed because of disordering of the cation and anion. 11B, 77Se NMR shifts and 1J(11B1H) coupling constants as well as IR- and Raman spectroscopic investigations convey further structural information. Structural data of 2 have been calculated by SCF methods. The anion of 2 may be viewed either as an adduct of Se with B3H8-, or as a bridge substituted selena derivative of B2H6.
    Notes: Bei der Reaktion zwischen elementarem Selen und MBH4 (1 : 1) (M = Na, Li) in Triglyme (Diglyme) entsteht unter Wasserstoffabspaltung M2[H3B—Se—Se—BH3] 1. Bei der Behandlung von 1 mit überschüssigem B2H6 oder THF · BH3 wird die Se—Se-Bindung gespalten und es entsteht unter erneuter Wasserstoffabspaltung M[H3B-μ2-Se(B2H5)] 2. Aus Na · 2 und [(C6H5)4P]Br entsteht [(C6H5)4P] · 2, welches tetragonal in der Raumgruppe I4 (Nr. 82) kristallisiert. Kation und Anion sind im Kristall fehlgeordnet. Strukturinformationen konnten aus den 11B-, 77Se- und 1J(11B1H)-Daten einerseits und den IR- und Raman-spektroskopischen Untersuchungen andererseits erhalten werden. Aus SCF-Rechnungen erhielten wir die Strukturparameter für das Anion 2. 2 kann sowohl als Addukt von Se an B3H8- als auch als brückensubstituiertes Selena-Derivat des B2H6 aufgefaßt werden.
    Additional Material: 3 Ill.
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  • 30
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 969-974 
    ISSN: 0044-2313
    Keywords: Copper(I) selenium tellurium halides ; chalcogen ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: CuSeTeCl, CuSeTeBr, and CuSeTeI: Compounds with ordered ∞1[SeTe] ScrewsThe hitherto unknown copper(I) chalcogen halides CuSeTeCl, CuSeTeBr and CuSeTeI have been prepared and their crystal structures were determined. The compounds of general composition CuSeTeX crystallize in the monoclinic system, space group P21/n (No. 14), Z = 4, a = 7.9796(9), b = 4.7645(8), c = 10.843(3) Å, β = 104.12(1)°, V = 399.8(1) Å3 (X = Cl), a = 8.155(3), b = 4.765(2), c = 11.286(4) Å, β = 104.21(3)°, V = 425.1(3) Å3 (X = Br) and a = 8.4370(9) b = 4.7652(5), c = 11.996(2) Å, β = 103.178(9)°, V = 469.6(1) Å3 (X = I). The crystal structures show infinite onedimensional screws YY′ of chalcogen atoms, with Y = Se and Y′ = Te alternately. The coordinations of Se and Te in these compounds are quite different.
    Notes: Die bisher unbekannten Kupfer(I)-chalkogenhalogenide CuSeTeCl, CuSeTeBr und CuSeTeI wurden erstmals erhalten und ihre Kristallstrukturen bestimmt. Sie kristallisieren monoklin, RG P21/n (Nr. 14), Z = 4, mit a = 7,9796(9), b = 4,7645(8) und c = 10,843(3) Å, β = 104,12(1)°, V = 399,8(1) Å3 (X = Cl), a = 8,155(3), b = 4,765(2) und c = 11,286(4) Å, β = 104,21(3)°, V = 425,1(3) Å3 (X = Br) sowie a = 8,4370(9), b = 4,7652(5) und c = 11,996(2) Å, β = 103,178(9)°, V = 469,6(1) Å3 (X = I). In den Kristallstrukturen liegen eindimensional unendliche Schrauben YY′ vor, mit alternierend Y = Se und Y′ = Te. Die Umgebungen von Se und Te sind deutlich verschieden.
    Additional Material: 3 Ill.
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