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.

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.

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 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.

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.

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.

23Na Spin-Lattice Relaxation Measurements in Dehydrated Na-X Zeolite

1996 ◽  
Vol 51 (5-6) ◽  
pp. 657-661 ◽  
Author(s):  
Mutsuo Igarashi ◽  
Noriaki Okubo ◽  
Shuichi Hashimoto ◽  
Deok Joon Cha ◽  
Ryozo Yoshizaki
Keyword(s):  
Relaxation Time ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
Relaxation Measurements ◽  
X Zeolite ◽  
Single Exponential

Abstract The spin-lattice relaxation time T1 of 23Na-NMR in a dehydrated Na-X zeolite has been measured from 20 to 300 K. The recovery curve is not single-exponential at all measured temperatures and T1-1 increases with the square of temperature around room temperature. The results are analyzed by assuming non-equivalent sites and by applying the theory of the Raman process based on covalency.

A Study of Complex Anionic Motions in (Me2NH2)2ZnCl4 Crystals by Means of Chlorine Nuclear Quadrupole Resonance Techniques

1990 ◽  
Vol 45 (3-4) ◽  
pp. 464-466 ◽  
Author(s):  
Hiroshi Yamamoto ◽  
Atsushi Ishikawa ◽  
Tetsuo Asaji ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transition ◽  
Relaxation Time ◽  
Transition Temperature ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Abstract Three 35Cl NQR frequencies were observed for (Me2NH2)2ZnCl4 at room temperature, indicating the existence of three crystallographically nonequivalent chlorines in the crystal. With decreasing temperature, the frequency of the lines increased almost linearly and disappeared below ca. 220 K near the reported phase transition temperature (ca. 215 K) detected on cooling. The three NQR lines faded out above room temperature because of the occurrence of rapid anionic reorientational motions disclosed from measurements of the 35Cl NQR spin-lattice relaxation time.

Orientation Dependence of the Nuclear Quadrupole Spin-lattice Relaxation of 23Na in NaNO2

1986 ◽  
Vol 41 (1-2) ◽  
pp. 370-373 ◽  
Author(s):  
S. Towta ◽  
D. G. Hughes
Keyword(s):  
Lattice Relaxation ◽  
Orientation Dependence ◽  
Spin Lattice Relaxation ◽  
Approach To Equilibrium ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Nuclear Quadrupole ◽  
Nuclear Quadrupole Spin ◽  
Nuclear Quadrupole Relaxation ◽  
Charge Calculations

The nuclear quadrupole relaxation probability W1 of 23Na in a single crystal of NaNO2 has been studied by applying a selective 180° pulse to the centre line and monitoring the exponential approach to equilibrium of the satellites. The orientation dependence of W1 at 170 K is similar in form to that at 298 K, indicating that the lattice motions responsible for the relaxation are similar at both temperatures. Ratios of the M-tensor components obtained by fitting the W1 data have been compared with the results of various point charge calculations. It indicates that the relaxation is primarily caused by interaction with the four nearest oxygen atoms and confirms that the NO2 groups oscillate and reorient primarily about the c axis.

Antimony NQR and Nuclear Magnetic Relaxation in Hexaammonium Dodecafluorotrisulfatotetraantimonate (III), (NH4)6 Sb4(SO4)3F12

1990 ◽  
Vol 45 (3-4) ◽  
pp. 541-544 ◽  
Author(s):  
Hideaki Chihara ◽  
Nobuo Nakamura
Keyword(s):  
Magnetic Relaxation ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Ammonium Ions ◽  
Spin Lattice ◽  
Resonance Frequencies ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Abstract Antimony nuclear quadrupole resonance frequencies in (NH4)6Sb4 (SO4)3 F12 crystals were measured as a function of temperature, and no evidence of phase transition was detected between 77 K and room temperature. However, the resonance frequencies do not follow the Bayer type exactly. Such an anomaly is attributed to the effect of rotation of ammonium ions which form hydrogen bonds of types N -H ···F and N -H ···O. In fact, the spin-lattice relaxation time of 1H and 19F has a minimum which is ascribed to the reorientation of NH+4 with an activation energy of 7.14 kJ mol -1. The switch model for the electric field gradient at Sb nuclei was examined.

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