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1Author    S. Lewicki, B. Szafrańska, Z. PająkRequires cookie*
 Title    Molecular Motion in Solid Tetrapropylammonium Bromide and Iodide  
 Abstract    The proton NMR second moment and spin-lattice relaxation time for tetrapropylammonium bromide and iodide have been measured over a wide temperature range. A solid-solid phase transition related to the onset of cation tumbling was found for both salts and confirmed by DTA. In the low temperature phases methyl group reorientation was evidenced. For iodide a dynamic nonequivalence of the methyl groups and the onset of ethyl groups motion was also discovered. 
  Reference    Z. Naturforsch. 47a, 1115—1118 (1992); received July 14 1992 
  Published    1992 
  Keywords    NMR, Molecular motions, Phase transitions 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1115.pdf 
 Identifier    ZNA-1992-47a-1115 
 Volume    47 
2Author    Barbara Szafrańska, Zdzisław PająkRequires cookie*
 Title     
 Abstract    o le c u la r M o tio n in S o lid T e tr a e th y l-a n d T e tra p ro p y la m m o n iu m T e tr a f lu o r o b o r a te s Proton and fluorine NMR second moments and spin-lattice relaxation times for polycrystalline tetraethyl-and tetrapropylammonium tetrafluoroborates have been measured over a wide range of temperatures. Solid-solid phase transitions were found for both compounds and confirmed by DSC. Methyl group C3 reorientation followed by more complex cation motions was evidenced in the low temperature phases. Overall cation reorientation characterises the high temperature phases of both compounds. Isotropic anion reorientation was found in both salts in both phases. 
  Reference    Z. Naturforsch. 50a, 584—588 (1995); received August 15 1994 
  Published    1995 
  Keywords    NMR, Molecular motions, Phase transitions 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0584.pdf 
 Identifier    ZNA-1995-50a-0584 
 Volume    50 
3Author    M. Grottel3, A. Kozakb, Z. PająkRequires cookie*
 Title    l H a n  
 Abstract    d 19F N M R S tu d y o f C a tio n a n d A n io n M o tio n s in G u a n id in iu m F lu o r o a n tim o n a te s Proton and fluorine NMR linewidths, second moments, and spin-lattice relaxation times of polycrystalline [C(NH2)3]2SbF5 and C(NH2)3SbF6 were studied in a wide temperature range. For the pentafluoroantimonate, C3-reorientation of the guanidinium cation and C4-reorientation of the SbF5 anion were revealed and their activation parameters determined. The dynamical inequivalence of the two guanidinium cations was evidenced. For the hexafluoroantimonate, two solid-solid phase transitions were found. In the low temperature phase the guanidinium cation undergoes C3 reorien­ tation while the SbF6 anion reorients isotropically. The respective activation parameters were derived. At high temperatures new ionic plastic phases were evidenced. 
  Reference    Z. Naturforsch. 50a, 742—748 (1995); received March 2 1995 
  Published    1995 
  Keywords    NMR, Molecular Motions, Phase transitions 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0742.pdf 
 Identifier    ZNA-1995-50a-0742 
 Volume    50 
4Author    M. Grottel, M. Szafrański, Z. PająkRequires cookie*
 Title    NMR Study of Cation Motion in Guanidinium Iodoplumbates  
 Abstract    Proton NMR second moments and spin-lattice relaxation times of polycrystalline C(NH 2) 3 PbI 3 and [C(NH 2) 3 ]2PbI 4 were studied in a wide temperature range. The order-disorder character of the existing solid-solid phase transitions was confirmed and for tetraiodoplumbate a new phase transition at 170 K was discovered. For both compounds a dynamical inequivalence and unusual high mobility of the guanidinium cations were revealed. For the reorientations discovered (NH 2 group flipping, C 3 in-plane reorientation and a tumbling) the activation parameters were determined. 
  Reference    Z. Naturforsch. 52a, 783—788 (1997); received October 6 1997 
  Published    1997 
  Keywords    NMR, Molecular Motions, Phase Transitions 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0783.pdf 
 Identifier    ZNA-1997-52a-0783 
 Volume    52 
5Author    Maria Zdanowska-Fnjczek, Malgorzata Grottel, Ryszard JakubasRequires cookie*
 Title    C1 NQR and l H NMR Studies of Molecular Motions in Guanidinium Salt of Chloroacetic Acid  
 Abstract    Multinuclear NQR and NMR techniques have been applied in order to study the molecular dynamics in [C(NH 2) 3 ](ClH 2 CCOO). The 35 C1 NQR frequency was measured over a wide range of temperature. The experimental results were described by using the theories of Bayer and Brown which take into account the torsional oscillations of the CClH 2 -group of the anion. A study of the proton NMR second moment as well as relaxation times T, and T Xp performed in a wide temperature range revealed an onset of the guanidinium cation reorientation around its two-fold symmetry axis. Activation parameters for this motion were determined. 
  Reference    Z. Naturforsch. 53a, 484—487 (1998); received March 24 1998 
  Published    1998 
  Keywords    NMR, NQR, Molecular Motion 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0484.pdf 
 Identifier    ZNA-1998-53a-0484 
 Volume    53 
6Author    J. Wąsicki, Z. Pająk, A. KozakRequires cookie*
 Title    Cation and Anion Reorientation at Phase Transition in Pyridinium Tetrafluoroborate  
 Abstract    Temperature dependences of and 19 F second moment and spin-lattice relaxation times for polycrystalline pyridinium tetrafluoroborate were measured. A phase transition was discovered at 202 K. A model of cation reorientation between inequivalent (low-temperature phase) and equiva-lent (high-temperature phase) equilibrium positions is proposed. Whether the anion reorients isotropically or about a symmetry axis cannot be decided. An analysis of cross-relaxation effects yielded activation parameters for cation and anion reorientation. The rotational correlation times for both ions converge just at the phase transition reaching the value of 10~ 10 s. 
  Reference    Z. Naturforsch. 45a, 33—36 (1990); received August 5 1989 
  Published    1990 
  Keywords    NMR, cross-relaxation, molecular motions, phase transitions 
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 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-0033.pdf 
 Identifier    ZNA-1990-45a-0033 
 Volume    45 
7Author    I. A. Kjuntsel, V. A. Mokeeva, I. G. Shaposhnikov, G. B. SoiferRequires cookie*
 Title    Influence of Thermoactivated Molecular Motions on the 35 C1 Quadrupole Relaxation  
 Abstract    The effect on the 35 C1 quadrupole relaxation of modulations of the electric field gradient by thermally activated motions of nearby nonbonding symmetric and asymmetric atomic groups has been investigated. This way the activation energy of the motions has been determined and the fraction of the electric field gradient influenced by the motions has been estimated. This fraction can be taken as a measure of the intensity of nonbonding interactions in solids. 
  Reference    Z. Naturforsch. 45a, 531—535 (1990); received August 23 1989 in revised form December 8 1989 
  Published    1990 
  Keywords    Molecular motion, Modulation effect, Nuclear quadrupole relaxation 
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 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-0531.pdf 
 Identifier    ZNA-1990-45a-0531 
 Volume    45 
8Author    Z. Szafrańska, A. Pająk, KozakRequires cookie*
 Title     
 Abstract    Proton and fluorine NMR second moments and spin-lattice relaxation times for polycrystalline tetrabutylammonium tetrafluoroborate have been measured over a wide range of temperatures at several Larmor frequencies. An analysis of cross-relaxation effects results in a determination of activation parameters for anion and cation reorientations. Three solid phases characterized by different ion dynamics are evidenced. M o le c u la r M o tio n in S o lid T e tra b u ty la m m o n iu m T e tr a f lu o r o b o r a te 
  Reference    Z. Naturforsch. 46a, 545—550 (1991); received March 14 1991 
  Published    1991 
  Keywords    NMR, Cross-relaxation, Molecular motions, Phase transitions 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0545.pdf 
 Identifier    ZNA-1991-46a-0545 
 Volume    46 
9Author    A. D. Gordeev, G. B. Soifer, A. P. ZhukovRequires cookie*
 Title    C1 NQR and Molecular Motion in Solid C 6 X 5 C1 (X = H, F)  
 Abstract    The 35 C1 NQR frequency and spin-lattice relaxation time of solid chlorobenzene and chloro-pentafluorobenzene at temperatures from 77 K to the melting points have been measured and explained by thermoactivated librations and reorientations of the molecules around the normal to their plane. The activation energies of these motions have been estimated. 
  Reference    Z. Naturforsch. 47a, 330—332 (1992); received July 18 1991 
  Published    1992 
  Keywords    NQR spectroscopy, Molecular motion, Benzene derivatives 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0330.pdf 
 Identifier    ZNA-1992-47a-0330 
 Volume    47 
10Author    S. Torre, P. FerloniRequires cookie*
 Title    Molecular Motion in Solid Tetramethylammonium Tetrafluoroborate  
 Abstract    Measurements of n B and NMR relaxation times, differential scanning calorimetry and thermomechanical analysis, carried out on polycrystalline (CH 3) 4 NBF 4 from room temperature to about 100 K, have permitted to discuss the crystal dynamics of this salt and to analyze the nature of the phase transition occurring at «150K. Moreover, by means of an evaluation of the n B quadrupole coupling constant, information about the position of the F atoms has been obtained. An explanation of the NMR data in terms of an order-disorder phase transition involving the F~ ions is given. 
  Reference    Z. Naturforsch. 47a, 721—727 (1992); received March 24 1992 
  Published    1992 
  Keywords    (CH 3 ) 4 NBF 4, Molecular motion, Phase transition 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0721.pdf 
 Identifier    ZNA-1992-47a-0721 
 Volume    47 
11Author    Barbara Szafrańska, Zdzisław PająkRequires cookie*
 Title    Molecular Motion in Solid Tetraethyl-and Tetrabutylammonium Perchlorates  
 Abstract    The proton N M R second moment and spin-lattice relaxation time for polycrystalline tetraethyl-and tetrabutylammonium perchlorates have been measured over a wide range of temperatures. Solid-solid phase transitions related to the onset of cation tumbling were found for both compounds and confirmed by DSC. In the low temperature phases methyl-group reorientation was evidenced. For tetrabutylammonium cation a dynamic nonequivalence of one methyl group is found. The geared motion of the alkyl chains related with the onset of successive C H 2-group reorientations is suggested. 
  Reference    Z. Naturforsch. 49a, 465—468 (1994); received December 7 1993 
  Published    1994 
  Keywords    N M R, Molecular motions, Phase transitions 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0465.pdf 
 Identifier    ZNA-1994-49a-0465 
 Volume    49 
12Author    A. D. Gordeev, A. N. Osipenko, G. B. SoiferRequires cookie*
 Title    C1 NQR in Solid Trichloroacetyl Halides  
 Abstract    By 35 C1 NQR the temperature dependences of the resonance frequencies and spin4attice relax-ation times for the 35 C1 nuclei have been studied in solid CCl 3 COHal (Hal = F, CI, Br, I). A linear correlation between the average 35 C1 NQR frequencies of the CC1 3 groups and the electronegativ-ities of the halogen atoms in the COHal groups has been discovered. The temperature-dependent NQR data reveal thermoactivated reorientations of the CCl 3 COHal molecules as a whole in the crystal lattice. The activation energies of this motion are found to lie in the range 31 -37 kJ mol 
  Reference    Z. Naturforsch. 51a, 751—754 (1996); received October 20 1995 
  Published    1996 
  Keywords    NQR spectroscopy, Molecular motion, Trichloroacetyl halides 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0751.pdf 
 Identifier    ZNA-1996-51a-0751 
 Volume    51 
13Author    Masao Hashimoto, Yuko Monobe, Hiromitsu Terao, Haruo Niki, Koichi ManoRequires cookie*
 Title    Phase Transition and Crystal Dynamics of 4-Bromobenzyl Alcohol  
 Abstract    For the title compound a phase transition from Phase II to Phase I (low and room temperature phases, respectively) was found at ca. 217 K. The temperature dependence of the 8 'Br NQR frequency and that of the dielectric constant showed anomalies at ca. 195 K that were tentatively attributed to a higher order phase transition. A similar anomaly was found at ca. 218 K for 4-chlorobenzyl alcohol which showed a II-I transition at 236 K. The dielectric dispersion observed for both compounds at low temperatures indicates an excitation of a molecular motion with the dielectric relaxation rate of ca. 1 kHz. The temperature dependence of the sl Br NQR frequencies of 2-and 3-bromobenzyl alcohol, measured at T > 77 K, gave no evidence of phase transition in their crystals. 
  Reference    Z. Naturforsch. 53a, 436—441 (1998); received March 24 1998 
  Published    1998 
  Keywords    NQR, Phase Transition, Molecular Motion, Dielectric Dispersion 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0436.pdf 
 Identifier    ZNA-1998-53a-0436 
 Volume    53 
14Author    Hiroyuki IshidaRequires cookie*
 Title    H and 19 F NMR Studies on Molecular Motions in Two Solid Phases of t-Butylammonium Tetrafluoroborate  
 Abstract    Differential thermal analysis (DTA), differential scanning calorimetry (DSC), and the temperature dependence of the spin-lattice relaxation time (T {) and the second moment (M 2) of 1 H and F NMR were studied in (CH3) 3 CNH 3 BF4 and (CH 3) 3 CND 3 BF 4 . DTA and DSC revealed a solid-solid phase transition at 219 K for (CH 3) 3 CNH3BF4 and at 221 K for (CH 3) 3 CND 3 BF 4 . The motions of cations and anions in the two solid phases were studied by T x and M 2 experiments. The motional modes of the ions and their motional parameters were determined. 
  Reference    Z. Naturforsch. 53a, 796—800 (1998); received May 30 1998 
  Published    1998 
  Keywords    Molecular motion, Phase transition, Nuclear magnetic resonance 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0796.pdf 
 Identifier    ZNA-1998-53a-0796 
 Volume    53 
15Author    Hiroyuki Ishida, Naoki Kumagae, Setsuko SatoaRequires cookie*
 Title    Motions of Ethylammonium Ions in Solid Ethylammonium Chloranilate Studied by 1H Nuclear Magnetic Resonance  
 Abstract    The motions of the ethylammonium ion in solid ethylammonium chloranilate, C2H5NH3 • Q H O 4CI2, are studied by *H NMR second moment (M2) and spin-lattice relaxation time {Tx) measurements. Re­ orientations of the CH3 group about the C-C bond axis and the NH3 group about C -N bond axis were observed and their motional parameters were evaluated. The internal rotational barriers of the CH3 and NH3 groups of an isolated C2H5NH3 ion were estimated from ab initio molecular orbital calculations. 
  Reference    Z. Naturforsch. 56a, 523 (2001); received April 30 2001 
  Published    2001 
  Keywords    Nuclear Magnetic Resonance, Molecular Motion, Ethylammonium Ion, HF 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0523.pdf 
 Identifier    ZNA-2001-56a-0523 
 Volume    56 
16Author    Makoto Kaga, Tetsuo Asaji, Ryuichi Ikeda, Daiyu NakamuraRequires cookie*
 Title    Chlorine Nuclear Quadrupole Relaxation and Cationic Motion in Trimethylsulfonium Hexachloroselenate(IV): [(CH 3 ) 3 Sl 2 SeCl^  
 Abstract    The 35 C1 NQR spin-lattice and spin-spin relaxation times, 7^ and T2Q, respectively, and the 'H NMR spin-lattice relaxation time T1H at 32 and 60 MHz were determined for [(CH3j3S]2SeCl6 as functions of temperature. The rapid decrease of observed above ca. 250 K with increasing temperature was attributed to the onset of reorientation of the [SeCl6] 2 " complex anion with the activation energy £a = 42 + 5 kJ mol -1 . When cooled from ca. 250 K, T1Q showed an anomalous decrease. This 7"1Q decrease was explained by electric field gradient modulation related to some cationic motion. Possible origins of the cationic motion are discussed. 
  Reference    Z. Naturforsch. 47a, 274—276 (1992); received July 19 1991 
  Published    1992 
  Keywords    Spin-lattice relaxation, NQR, NMR, EFG modulation, Molecular motion 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0274.pdf 
 Identifier    ZNA-1992-47a-0274 
 Volume    47 
17Author    P. J. Sebastião, A. C. Ribeiro, H. T. Nguyen, F. NoackRequires cookie*
 Title    Proton NMR Relaxation Study of Molecular Motions in a Liquid Crystal with a Strong Polar Terminal Group  
 Abstract    Liquid crystalline compounds containing a cyano terminal group often exhibit peculiar molecular organizations of their mesophases. In this work we present proton NMR relaxation studies, per-formed by means of standard NMR and fast field-cycling NMR techniques, in the nematic (N) and bilayered smectic-,4 phase (S^ 2) of 4-pentyl-phenyl 4'-cyanobenzoyloxy-benzoate. The field-cycling measurements were used to clarify the relaxation behaviour in the low Larmor frequency range, where conventional techniques are not applicable. Self-diffusion and rotational reorientations are found to be the essential relaxation mechanisms at MHz frequencies in the smectic mesophase, while the contribution of collective modes appears only at lower frequencies in the kHz range. In the nematic mesophase the order director fluctuations mechanism dominates the relaxation dispersion up to 10 MHz, where the rotational reorientations become important, with minor corrections from the self-diffusion process. The agreement between the experimental findings and model fits could be improved by an additional relaxation mechanism in the kHz regime, ascribed to the interaction between protons and fast relaxing quadrupolar nitrogen 14 N nuclei. Though all four processes are present in the nematic and smectic-/l 2 phases, the overall 7\ frequency dependence is quite different in the two cases. This behaviour is discussed in terms of available theoretical calculations of the proton relaxation dispersion in liquid crystals, and it is also compared with data known from other cyano compounds. 
  Reference    Z. Naturforsch. 48a, 851—860 (1993); received April 22 1993 
  Published    1993 
  Keywords    NMR, Proton relaxation, Smectic-/! 2, Molecular motions, Bilayer smectic 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0851.pdf 
 Identifier    ZNA-1993-48a-0851 
 Volume    48 
18Author    Stefan Jurga, Kazimierz Jurga, EduardC. Reynhardt, Piotr KatowskiRequires cookie*
 Title    A Proton NMR Study of n-Decylammonium Chain Dynamics in the Perovskite-type Layered Compound (C 10 H 21 NH3) 2 CdCl4  
 Abstract    A detailed proton second moment and spin-lattice relaxation time investigation of the bilayered compound (C 10 H 21 NH 3) 2 CdCl 4 is reported. In the low temperature phase the methyl group exe-cutes a classical threefold reorientation, while the NH 3 group is involved in a similar reorientation in an asymmetric potential well. Evidence for defect chain motions in this phase has been found, and infomation regarding the potential wells associated with these motions has been extracted from the data. In the high temperature phase, slow chain defect motions and fast fourfold reorientations of chains about their long axes, parallel to the normal to the bilayer, have been observed. 
  Reference    Z. Naturforsch. 48a, 563—569 (1993); received October 9 1992 
  Published    1993 
  Keywords    Bilayered compounds, Phase transition, Spin-lattice relaxation, Molecular motions, Defect motions 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0563.pdf 
 Identifier    ZNA-1993-48a-0563 
 Volume    48 
19Author    T. Ueda, K. Shimizu, H. Ohki, T. OkudaRequires cookie*
 Title    C CP/MAS NMR Study of the Layered Compounds [C 6 H 5 CH 2 CH 2 NH3] 2 [CH 3 NH 3 ] fI _ 1 Pb n l3 n+1 (n = 1, 2)  
 Abstract    19, 1996 13 C CP/MAS NMR spectra were measured on the layered compounds [C 6 H 5 CH 2 CH 2 NH 3 ] 2 [CH 3 NH 3 ] n _ 1 Pb"I 3n + j (w = 1, 2). The linewidth of the resonance peak corresponding to the phenyl carbons changed with temperature. The maximum broadening took place at 363 K for both com-pounds. The activation energy £ a for the reorientation of the phenyl group was determined to be 25 kJ mol" 1 for n — 1 and 26 kJ mol" 1 for n = 2. The frequency factor t 0 was evaluated from the linewidth at 363 K. The value of the second moment, estimated from the maximum linewidth, was interpreted by assuming a 180° flip of the phenyl group around its two-fold axis. The similarity of the activation energies for the reorientation of the phenyl group suggested that the local structure and the molecular motion of the organic cations is little affected by the difference in the sub-structure of the inorganic layer in those compounds. 
  Reference    Z. Naturforsch. 51a, 910—914 (1996); received March 
  Published    1996 
  Keywords    13 C CP/MAS NMR, Molecular motion, Layered compounds Activation parameters, Local structure 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0910.pdf 
 Identifier    ZNA-1996-51a-0910 
 Volume    51 
20Author    Naohiro Yoshida, Noriko Onoda-Yamamuro, Shin'. Ichi Ishimaru, Keizo Horiuchi, Ryuichi IkedaRequires cookie*
 Title    Temperature Dependence of 2 H Quadrupole Coupling Constants in 2 H 2 0 and Ionic Motions in Crystalline IM( 2 H 2 0) 6 ] ISnCl 6 ] (M: Mg, Ca), Studied by 2 H NMR and Neutron Powder Diffraction  
 Abstract    The temperature dependence of 2 H NMR spectra was measured at 130-430 K on [M(D 2 0) 6 ] [SnCl 6 ] (M : Mg, Ca) (rhombohedral, space group: R3), and neutron powder diffraction on the Mg salt was performed at room temperature. Based on the accurate orientation of D 2 0 molecules in an octahedral cation, spectra with a large asymmetry parameter rj, observed around 200 K, were explained by a model of 180° flip of water molecules. Another motional narrowing observed above room temperature was assigned to a cationic overall reorientation about the C 3 -axis. 
  Reference    Z. Naturforsch. 53a, 473—479 (1998); received October 31 1997 
  Published    1998 
  Keywords    2 H NMR, Neutron Diffraction, Molecular Motion, Quadrupole Coupling Constant, Spectrum Lineshape 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0473.pdf 
 Identifier    ZNA-1998-53a-0473 
 Volume    53 
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