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1Author    H.-R Blank, M. Frank, J. Heindl, M. Kaltenhäuser, H. Köchner, W. Kreische, N. Müller, S. Porscher, T. WagnerRequires cookie*
 Title    A Simple Model to Explain 19 F-TDPAD Amplitude Characteristics  
 Abstract    Since many years the 19 F-TDPAD method (TDPAD = time differential perturbed angular distri-bution) has been used to investigate electric field gradients in fluorine compounds. In these experi-ments always a strong reduction of the observed interaction amplitudes is observed. To explain these characteristics, a simple kinematic model is suggested. 
  Reference    Z. Naturforsch. 47a, 389—394 (1992); received July 29 1991 
  Published    1992 
  Keywords    TDPAD, Quadrupole interaction, Fluorine, Perturbation amplitude, Temperature dependence 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0389.pdf 
 Identifier    ZNA-1992-47a-0389 
 Volume    47 
2Author    Tsutomu Okuda, Yoshihiro Kinoshita, Hiromitsu Terao, Koji YamadaRequires cookie*
 Title    Structure and Bonding of Bromoantimonate (III) Complexes with Unusual Valency by Means of NQR and Powder X-Ray Diffraction  
 Abstract    NQR and powder X-ray diffraction were observed for several bromoantimonate (III) complexes which contain C"H2n+ jNF^ (n = 1 -3) or (C"H2lt + 1)2N H 2 (n = 1 -4) as a cation. The bond character, anion structure, crystal structure, and phase transition are discussed on the basis of the three-center-four-electron bond. A good correlation was found between the halogen NQR frequency and the Sb-X bond length. 
  Reference    Z. Naturforsch. 49a, 185—192 (1994); received July 23 1993 
  Published    1994 
  Keywords    81Br NQR, Temperature dependence, Phase transition, Crystal structure 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0185.pdf 
 Identifier    ZNA-1994-49a-0185 
 Volume    49 
3Author    Ingo Biertümpel, Hans-Herbert SchmidtkeRequires cookie*
 Title    Evaluation of Luminescence Decay Measurements Probed on Pure and Doped Pt(IV) Hexahalogeno Complexes. II. Molecular Properties Obtained from Temperature Dependent Lifetime Curves  
 Abstract    Lifetime measurements down to nearly liquid helium temperatures are used for determining energy levels and transition rates between excited levels and relaxations into the ground state. Energies are obtained from temperature dependent lifetimes by fitting experimental curves to model functions pertinent for thermally activated processes. Rates are calculated from solutions of rate equations. Similar parameters for pure and doped Pt(IV) hexahalogeno complexes indicate that excited levels largely belong to molecular units. Some of the rates between excited states are only somewhat larger than decay rates into the ground state, which is a consequence of the polyexponential decay measured also at low temperature (2 K). In the series of halogen complexes, the rates between spinorbit levels resulting from 3 Ti g increase from fluorine to bromine, although energy splittings become larger. Due to the decreasing population of higher excited states in this series, K^PtFö shows a tri-exponential, K^PtClö a bi-exponential and FoPtBre a mono-exponential decay. In the latter case the population density of higher excited states relaxes so fast that emission occurs primarily from the lowest excited F}(3 Ti 9) level. Phase transitions and emission from chromophores on different sites can also be observed. 
  Reference    Z. Naturforsch. 52a, 447—456 (1997); received January 22 1997 
  Published    1997 
  Keywords    Pt(IV) complexes, luminescence decay, temperature dependence 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0447.pdf 
 Identifier    ZNA-1997-52a-0447 
 Volume    52 
4Author    N. Nissen, J. Doose, A. Guarnieri, H. Mäder, V. N. Markov, G. Yu, Golubyatnikov, 1. Leonov, V. N. Shanin, A. F. KrupnovRequires cookie*
 Title    Foreign Gas Broadening Studies of the J' <-J = 1 0 Rotational Line of CO by Frequency and Time Domain Techniques  
 Abstract    The collisional broadening of the J' J = 1 <— 0 rotational line of carbon monoxide by the buffer gases He, Ne, Ar, Kr, CO, N 2 , 0 2 , and air has been studied at room temperature. Two different experimental techniques in time-and frequency-domain, respectively, were used. The obtained data are in good agreement. Time-domain investigations on the temperature dependence of the foreign gas broadening parameters are also presented. 
  Reference    Z. Naturforsch. 54a, 218—224 (1999); received December 14 1998 
  Published    1999 
  Keywords    CO, Line Broadening, Buffer Gases, Temperature Dependence 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0218.pdf 
 Identifier    ZNA-1999-54a-0218 
 Volume    54 
5Author    L. Xie, W. H. SaundersRequires cookie*
 Title    Is  
 Abstract    o to p e E ffe c ts in K in e tic E n o la te F o r m a tio n fro m 2 -P e n ta n o n e a n d 2 -P e n t a n o n e -l , l , l -d 3 This paper is dedicated to Professor Jacob Bigeleisen on the occasion of his 70th birthday 2-Pentanone and 2-pentanone-l,l,l-d3 were treated with three-fold excesses of lithium diiso-propylamide (LDA) or lithium hexamethyldisilazide (LHMDS) in tetrahydrofuran (THF) with and without hexamethylphosphoric triamide (HMPA, 3 mol per mol of base) at temperatures ranging from 24 to — 70 °C. The deuterium kinetic isotope effects calculated from the product ratios (mea­ sured by GLC as trimethylsilyl enol ethers) showed a range of temperature dependences: none (LDA in THF), attenuated with A^jA^ = 2.53 (LHMDS in THF), and normal with /1H//1D~0.6 indicating moderate tunneling (LDA and LHMDS in THF-HMPA). The variation in temperature dependence is attributed to reaction via multiple base species in which HMPA affects the equilibria between the base species. 
  Reference    Z. Naturforsch. 44a, 413 (1989); received January 13 1989 
  Published    1989 
  Keywords    Isotope Effects, Kinetic Enolates, Temperature Dependence, Lithium Dialkylamide Bases 
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 TEI-XML for    default:Reihe_A/44/ZNA-1989-44a-0413.pdf 
 Identifier    ZNA-1989-44a-0413 
 Volume    44