Chlorine Nuclear Quadrupole Relaxation due to the Motion of Pyridinium Cations in Pyridinium Hexachlorometallates(IV): (pyH)2 MCl6 (M = Sn, Pb, Te)

1990 ◽  
Vol 45 (3-4) ◽  
pp. 477-480 ◽  
Author(s):  
Yutaka Tai ◽  
Tetsuo Asaji ◽  
Daiyu Nakamura
Keyword(s):  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Reorientational Motion ◽  
Quadrupole Relaxation ◽  
Potential Wells ◽  
Spin Lattice ◽  
Pyridinium Cations ◽  
Nuclear Quadrupole Relaxation

Abstract The temperature dependence of the chlorine quadrupole spin-lattice relaxation time T1Q was observed for one of the three 35Cl NQR lines of (pyH)2 MCl6(M = Sn, Pb, Te). Each T1Q curve can be devided into three temperature regions. In the low-and high-temperature regions, T1Q is dominantly determined by the relaxation mechanism due to the libration and reorientation of [MCl6]2- , respectively. In the intermediate temperature region, T1Q results from the modulation of the electric field gradient by the motion of the neighboring pyridinium cations. This way the reorientational motion of the cation between potential wells with nonequivalent depths is precisely characterized.

81Br Nuclear Quadrupole Relaxation in Aluminium Tribromide

1995 ◽  
Vol 50 (8) ◽  
pp. 737-741 ◽  
Author(s):  
Noriaki Okubo ◽  
Mutsuo Igarashi ◽  
Ryozo Yoshizaki
Keyword(s):  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
Nuclear Spin Lattice Relaxation ◽  
Nuclear Quadrupole ◽  
Nuclear Quadrupole Relaxation

Abstract The 81Br nuclear spin-lattice relaxation time in AlBr3 has been measured between 8 K and room temperature. The result is analyzed using the theory of the Raman process based on covalency. A Debye temperature of 67.6 K and covalency of 0.070 and 0.072 for terminal and 0.022 for bridging bonds are obtained. The correspondence of the latter values to those obtained from the NQR frequencies is low, in contrast to the previously examined compounds.

scholarly journals 79Br Nuclear Quadrupole Relaxation in the High Temperature Modification of Niobium Pentabromide

1992 ◽  
Vol 47 (6) ◽  
pp. 713-720 ◽  
Author(s):  
Noriaki Okubo ◽  
Harutaka Sekiya ◽  
Chiaki Ishikawa ◽  
Yoshihito Abe
Keyword(s):  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
35Cl Nqr ◽  
High Temperature Modification ◽  
Nuclear Quadrupole Relaxation

AbstractThe spin-lattice relaxation time of 79Br NQR has been measured between 4.2 K and room temperature. The result is compared with that of 35Cl NQR in NbCl5. The origin of the relaxation is attributed to the quadrupolar interaction and the temperature dependence is explained by the Raman process. The Debye temperature is determined to be 94 K and the relaxation time is related with the NQR frequency through the covalency.

Chlorine Nuclear Quadrupole Relaxation and Cationic Motion in Trimethylsulfonium Hexachloroselenate(IV): [(CH3)3S]2SeCl6

1992 ◽  
Vol 47 (1-2) ◽  
pp. 274-276
Author(s):  
Makoto Kaga ◽  
Tetsuo Asaji ◽  
Ryuichi Ikeda ◽  
Daiyu Nakamurab
Keyword(s):  
Complex Anion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Nuclear Quadrupole ◽  
Increasing Temperature ◽  
Nuclear Quadrupole Relaxation

AbstractThe 35Cl NQR spin-lattice and spin-spin relaxation times, T1Q and T2Q, respectively, and the 1HNMR spin-lattice relaxation time T1H at 32 and 60 MHz were determined for [(CH3)3S]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 Ea = 42 + 5 kJ mol -1 . When cooled from ca. 250 K, T1Q showed an anomalous decrease. This T1Q decrease was explained by electric field gradient modulation related to some cationic motion. Possible origins of the cationic motion are discussed

35Cl NQR Spin-Lattice Relaxation Mechanism in Ni(H2O)6SnCl6 and Mg(H2O)6SnCl6 Crystals

1994 ◽  
Vol 49 (1-2) ◽  
pp. 286-290 ◽  
Author(s):  
Keizo Horiuchi
Keyword(s):  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Reorientational Motion ◽  
Spin Lattice ◽  
Room Temper Ature ◽  
35Cl Nqr ◽  
Steep Decrease ◽  
Octahedral Cations

Abstract The 35Cl NQR spin-lattice relaxation mechanism in isomorphous Ni(H2O)6SnCl6 and Mg(H2O)6SnCl6 crystals is reported. The spin-lattice relaxation time T1Q in the Ni compound is determined mainly by a paramagnetic relaxation. However, above ca. 400 K T1Q decreased rapidly and a log vs. T1 curve was almost linear. This steep decrease of T1Q was explained by reorientational motions of the anions with an activation energy of 73 kJ mol-1. In addition, a double minimum in T1Q, which can be interpreted as arising from the fluctuation o f the electric field gradient (EFG) at the chlorine site caused by cationic thermal motions, was observed around room temper ature. The temperature dependence of the 35Cl NQR T1Q in the Mg salt is re-analysed in the light of the EFG -modulation effect caused by a 180° flip motion of the H2O molecules and an overall reorientational motion of the [Mg(H2O)6]2+ octahedral cations as a whole.

35Cl Nuclear Quadrupole Relaxation in Pyridinium Hexachlorostannate (IV)

1988 ◽  
Vol 43 (11) ◽  
pp. 1002-1004 ◽  
Author(s):  
Yutaka Tai ◽  
Atsushi Ishikawa ◽  
Keizo Horiuchi ◽  
Tetsuo Asaji ◽  
Ryuichi Ikeda
Keyword(s):  
Sharp Decrease ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Relaxation ◽  
Quadrupole Spin ◽  
Spin Lattice ◽  
Nuclear Quadrupole ◽  
Complex Anions ◽  
Nuclear Quadrupole Relaxation

AbstractThe temperature dependence of the 35Cl quadrupole spin-lattice relaxation time T1Q is reported for the three known resonance lines of pyridinium hexachlorostannate (IV). With increasing temper­ature, a sharp decrease of T1Q is observed below the phase transition temperature of 331 K. This decrease can be explained by reorientational motions of the complex anions. The activation energy for the motions is determined as 97 and 63 kJmol-1 from the T1Q data obtained from the highest-frequency resonance line and the remaining two lines, respectively. The two different barriers observed for the reorientation of a single anion suggest the existence of anisotropy of the anionic motion. An anomalous T1Q vs. T-1 relation observed in an intermediate-temperature region is discussed by referring to the cationic motion.

35Cl Nuclear Quadrupole Relaxation in Antimony Trichloride

1994 ◽  
Vol 49 (6) ◽  
pp. 680-686 ◽  
Author(s):  
Noriaki Okubo ◽  
Yoshihito Abe
Keyword(s):  
Low Temperatures ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Antimony Trichloride ◽  
Spin Lattice Relaxation ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
Nuclear Quadrupole ◽  
Nuclear Quadrupole Relaxation

Abstract The 35Cl NQR frequency and spin-lattice relaxation time in SbCl3 have been measured between 10 K and the melting point. The relaxation at low temperatures is attributed to the Raman process. A Debye temperature of 141 K and covalencies 0.390 and 0.356 are obtained. The latter values correspond well to those obtained from the NQR frequencies. For the relaxation above 200 K two more mechanisms are considered.

A nuclear magnetic resonance investigation of solid tetraphosphorus trisulphide

1978 ◽  
Vol 364 (1719) ◽  
pp. 553-567 ◽  
Keyword(s):  
Phase 1 ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Minor Role ◽  
High Resolution Spectrum ◽  
Basal Nuclei ◽  
Spin Lattice ◽  
A Minor

The 31 P n. m. r. spectrum and spin–lattice relaxation time in polycrystalline P 4 S 3 have been measured between 77 and 500 K in the range 7 to 25 MHz. In phase II the 31 P n. m. r. spectra and second moments are dominated by the anisotropic chemical shift interactions. Close to the first-order phase transition at 314 K the spectra are narrowed by reorientation of the molecules about their triad axes. This motion also generates anisotropicshift spin-lattice relaxation notable for its absence of frequency dependence. The activation energy of this motion was found to be 34 kJ mol -1 . Nuclear dipolar interactions play only a minor role. In phase 1 the molecules exhibit rapid quasi-isotropic reorientation and diffusion. The anisotropic broadening interactions are averaged out and an AB 3 high-resolution spectrum of a doublet and quartet are resolved at 420 K, well below the melting point, 446 K. In this phase the spin–rotation interaction relaxation mechanism becomes dominant. Taking advantage of the remarkable motional narrowing in this compound we report the first solid-state n. m. r. J spectrum. This spectrum, recorded at 410 K, allowed the J coupling between apical and basal nuclei in solid P 4 S 3 to be measured accurately, 70.4 ± 0.5 Hz.

1HNMR Study on the Motion of NH4+ in Ferroelectric NH4H(ClH2CCOO)2 and Mixed (NH4)1-xRbxH(ClH2CCOO)2 (x = 0.15)

2002 ◽  
Vol 57 (11) ◽  
pp. 883-887 ◽  
Author(s):  
M. Zdanowska-Fra̡czek ◽  
A. Kozaka ◽  
R. Jakubasb ◽  
J. Wa̡sickia ◽  
R. Utrechta
Keyword(s):  
Relaxation Time ◽  
Group Dynamics ◽  
Nmr Relaxation ◽  
Activation Parameters ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Temperature Dependent ◽  
Spin Lattice

Temperature-dependent proton NMR relaxation time measurements have been performed at 60 MHz in order to study the NH4+ dynamics in ferroelectric NH4H(ClH2CCOO)2 and mixed Rbx(NH4)1-x(ClH2CCOO)2, where x = 0.15. The data indicate that the dominant relaxation mechanism for the NMR spin-lattice relaxation time T 1 in both crystals involves simultaneous NH4 group reorientation about their C2 and C3 symmetry axis in the paraelectric phase. Details of the NH4+reorientation have been inferred from analysis of temperature dependence of T1 assuming the Watton model. The activation parameters of the motionshave been determined.It has been found that the substitution of Rb does not change the activation parameters of the NH4 group dynamics.

1H Nmr Study Of Molecular Motions In Thiourea Pyridinium Nitrate Inclusion Compound

2004 ◽  
Vol 59 (7-8) ◽  
pp. 505-509 ◽  
Author(s):  
M. Grottela ◽  
A. Kozak ◽  
A. Pajzderska ◽  
W. Szczepański ◽  
J. Wąsicki
Keyword(s):  
Inclusion Compound ◽  
Activation Parameters ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
High Temperature Phase ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Spin Lattice ◽  
Nmr Study ◽  
Pyridinium Cations

The proton NMR second moment and spin-lattice relaxation time have been studied for polycrystalline thiourea pyridinium nitrate inclusion compound and its perdeuderated analogues in a wide temperature range. The reorientation of two dynamically different pyridinium cations around their pseudohexagonal symmetry axis taking place over inequivalent barriers have been revealed in the low-temperature phase. Activation parameters for these motions have been derived. A symmetrization of the potential barriers has been observed at the transition from intermediate to the high temperature phase. The motion of thiourea molecules has been also evidenced, but could not be unambiguously described.

Pressure dependence of nuclear quadrupole relaxation. I. 63Cu relaxation in cuprous oxide

1969 ◽  
Vol 47 (3) ◽  
pp. 309-313 ◽  
Author(s):  
R. L. Armstrong ◽  
K. R. Jeffrey
Keyword(s):  
Pressure Dependence ◽  
Cuprous Oxide ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Powdered Sample ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Charge Model ◽  
Nuclear Spin Lattice Relaxation

The pressure dependence of the nuclear spin lattice relaxation time of the 63Cu nuclei in a powdered sample of cuprous oxide is reported at two temperatures for hydrostatic pressures in the range 1 to 5000 kg cm−2. It is shown that the experimental value of T1 at atmospheric pressure can be accounted for on the basis of an ionic point charge model for cuprous oxide. The variation of T1 with pressure is discussed on the basis of this model.

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