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  • Inorganic Chemistry  (14)
  • 36.40  (3)
  • 14.80.Pb  (2)
  • 1
    ISSN: 1434-601X
    Keywords: 13.10.+q ; 12.20.Fv ; 14.80.Pb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-601X
    Keywords: 14.80.Pb ; 13.10. + q ; 12.20.Fv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 6 (1987), S. 193-198 
    ISSN: 1434-6079
    Keywords: 31.15 ; 36.40 ; 82.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 6 (1987), S. 287-292 
    ISSN: 1434-6079
    Keywords: 31.20 ; 36.40 ; 82.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 15 (1990), S. 79-86 
    ISSN: 1434-6079
    Keywords: 31.20 ; 36.40 ; 82.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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).
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 406 (1974), S. 307-311 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Vibrational Spectrum of Tetra-thiomethyl-phosphoniuin-hexachloroantimonatePreparation, properties and vibrational spectrum of Tetra-thiomethyl-phosphonium-hexachloroantimonate are reported. The kind of bonding in the ion is brief discussed.
    Notes: Es wird über die Darstellung, Eigenschaften und Schwingungsspektren des Tetra-thiomethyl-phosphonium-hexachloroantimonats berichtet. Die Bindungsverhältnisse werden kurz diskutiert.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 442 (1978), S. 221-224 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: About the Fluorescence Thermochromism of Acetonitrile Copper Iodide with Dibenzo-18-Crown-6Copper iodide reacts in actonitrile solution with dibenzo-18-crown-6 to form a compound,(CuJ)4(CH3CN)4(db-18-c-6), which fluoresces yellow at 298K, but pink at 77 K. It decomposes at 55.3°C. (5 Torr) by lost of acetonitrile and a heterogeneous mixture of copper iodide and polyether results. In absence of dibenzo-18-crown-6, copper iodide forms with acetonitrile a heterogeneous mixture of copper iodide and polyether results. In absence of dibenzo-18-crown-6, copper iodide forms with acetonitrile a solvate CuJ. CH3CN. It also shows fluorescence thermochromism (yellow at 298 K, but green at 77 k) but decomposes at 0°C and 760 Torr.The luminescences pectra of the macrocyclic polyether complex at 298 K is redshifted. This probably results from intersection between the crown and the acetonitrile copper iodide.
    Notes: Kupferjodid bildet in Acetonitril mit Dibenzo-18-Krone-6 eine Verbindung der Zusammensetzung (CuJ)4(CH3CN)4(db-18-c-6), die bei Raumtemperatur gelb, bei 77K rosa fluoresziert. Sie zersetzt sich bei 55,3°C (5 Torr) unter Verlust von Acetonitril zu einem heterogenen Gemenge aus Kronenäther Kupferjodid.In Abwesenheit von Kronenäther bildet Kupferjodid in Acetonitril ein Solvat CuJ · CH3CN. Es ist ebenfalls fluoreszenzthermochrom (gelb bei 298 K, grün bei 77 K) und zersetzt sich allerdings schon bei 0°C( 760 Torr). Das Lumineszenzspektrum des makrocyclischen Polyätherkomplexes ist bei 298 K rotverschoben, was wahrscheinlich auf die Wechselwirkung des Kronenäthers mit dem Acetonitrilo-Kupferjodid zurückzuführen ist.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 389 (1972), S. 269-279 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The vibration spectra (IR and RAMAN) are reported for OPF2(CH3), OPF(CH3)2, SPF2(CH3), SPF(CH3)2 and SPF2(C2H5) and assigned to the normal vibrations. For these compounds all valence force constants are calculated by a simplified valence force field. Substitution of fluorine atoms by the methyl group causes a diminuation of all force constants. There is a clear difference between Δf P—CH3 (- 18%) and Δf X =P and Δf P—F (-30%). The P—CH3 bond is incapable to form dπ—pπ-bonds. Therefore the diminuation of f P—CH3 is caused only by the inductive effect.
    Notes: Von OPF2(CH3), OPF(CH3)2, SPF2(CH3), SPF(CH3)2 und SPF2(C2H5) werden die Schwingungsspektren (meistens IR und RAMAN) mitgeteilt und den Grundschwingungen zugeordnet. Gemeinsam mit den Endgliedern XPF3 und XP(CH3)3 (X = O, S) werden die Valenzkraftkonstanten nach einem Näherungsverfahren berechnet. Sämtliche Kraftkonstanten nehmen beim Ersatz von Fluor durch die Methylgruppe stark ab. Für f P—CH3 (-18%) ergibt sich gegenüber f P = X und f P—F (-30%) ein deutlicher Unterschied, bedingt durch die Unfähigkeit der CH3-Gruppe zur Ausbildung von dπ—pπ-Bindungen. Die Abnahme für f P—CH3 wird auf den induktiven Effekt allein zurückgeführt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The vibrational spectra (IR and RAMAN) from XP(N(CH3)2)2Cl and XP(N(CH3)2)Cl2 (X = O, S) are reported. The spectra are discussed and assigned to the normal vibrations in connection with the spectra of XP(N(CH3)2)3 and XPCl3. The valence force constants are calculated by a simplified valence force field. f P-NR2 and f P-Cl decrease slightly on substitution of the NR2 group by chlorine; f P-X, on the contrary, increases very distinctly. This is caused by the change from an element of the second period to an element of the third one.
    Notes: Es werden die Schwingungsspektren (IR und RAMAN) von XP(N(CH3)2)2Cl und XP(N(CH3)2)Cl2 mitgeteilt und in Zusammenhang mit den Spektren der Randglieder dieser Reihe XP(N(CH3)2)3 und XPCl3 (X = O, S) diskutiert und zugeordnet. Auf dieser Grundlage wurden nach einem Näherungsverfahren die Valenzkraftkonstanten ermittelt. Während f P-NR2 und f P-Cl beim Ersatz der NR2-Gruppen durch Chlor leicht abnehmen. zeigen beide f P-X eine starke Zunahme. Da beide Bindungspartner (NR2 und Cl) ungefähr gleiche Elektronegativität besitzen, so muß die starke Zunahme von f P-X auf die Zugehörigkeit der beiden Bindungspartner zu verschiedenen Perioden des Systems zurückgeführt werden.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vibrational Spectra and Force Constants of the Series OPF3—OP(OCH3)3 and SPF3—SP(OCH3)3The vibrational spectra (IR and RAMAN) for OPF2(OCH3), OPF(OCH3)2, SPF2(OCH3) and SPF(OCH3)2 are reported and assigned to the normal vibrations. The valence force constants are calculated by a simplified valence force field. The changes of the bonds are discussed.
    Notes: Es werden die Schwingungsspektren (IR und RAMAN) von OPF2(OCH3), OPF(OCH3)2, SPF2(OCH3) und SPF(OCH3)2 mitgeteilt und die Zuordnung zu den Grundschwingungen vorgenommen. Nach einem Näherungsverfahren werden die Valenzkraftkonstanten berechnet und die Bindungsverhältnisse diskutiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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