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

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 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.

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.

Temperature Dependences of NQR Frequencies and Nuclear Quadrupole Relaxation Times of Chlorine in 2,6-Lutidinium Hexachlorotellurate (IV) as Studied by Pulsed NQR Techniques

1990 ◽  
Vol 45 (3-4) ◽  
pp. 485-489
Author(s):  
Keizo Horiuchi ◽  
Takashige Shimizu ◽  
Hitomi Iwafune ◽  
Tetsuo Asaji ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transition ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Resonance Frequencies ◽  
Temperature Dependences ◽  
Nuclear Quadrupole

Abstract The temperature dependences of the 35Cl NQR frequencies vQ and the nuclear quadrupole spin-lattice relaxation times T1Q in 2,6-lutidinium hexachlorotellurate (IV) was observed at various temperatures between 80 and 343 K. This crystal undergoes a phase transition at Tc = 229 K. A single and three pairs of 35Cl NQR frequencies were observed above and below Tc , respectively. The hysteresis of the phase transition and a discontinuity in the temperature dependence of the resonance frequencies at Tc indicate that this phase transition is of first order. Although the resonance frequencies of the pairs in the low temperature phase are very close to one another, T1Q and below Tc could be accurately determined by measuring the Fourier transform spectra of each line. Above ca. 250 K, T1Q showed an exponential decrease which is attributable to the overall reorientational motion of [TeCl6]2- with an activation energy of 82 kJ mol-1

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.

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.

NUCLEAR QUADRUPOLE RESONANCE STUDIES IN CUPROUS OXIDE

1966 ◽  
Vol 44 (10) ◽  
pp. 2315-2328 ◽  
Author(s):  
K. R. Jeffrey ◽  
R. L. Armstrong
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Cuprous Oxide ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Moments ◽  
Spin Lattice ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

The 63Cu and 65Cu pure nuclear quadrupole resonance transitions have been investigated in a powder sample of cuprous oxide from 4.2 °K to 298 °K. The observed decrease in resonance frequency with increasing temperature is discussed in terms of the theory developed by Bayer and Kushida. The spin-lattice relaxation-time measurements above 20.4 °K are interpreted in terms of a coupling of the lattice phonons to the nuclear quadrupole moments via two phonon Raman processes. A rough estimate of the Debye temperature is made. The measured relaxation times at 4.2 °K are an order of magnitude shorter than predicted by the spin-phonon mechanism. Two other mechanisms are discussed: (i) a coupling of the spins to torsional oscillations; (ii) a coupling of the spins to paramagnetic impurities.

Incommensurability and Domain Structure of K2SbF5

2002 ◽  
Vol 57 (6-7) ◽  
pp. 456-460
Author(s):  
A. M. Panich ◽  
L. A. Zemnukhova ◽  
R. L. Davidovich
Keyword(s):  
Relaxation Time ◽  
Phase Transitions ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Spin Lattice ◽  
Relaxation Measurements ◽  
Increasing Temperature

Phase transitions and incommensurability in K2SbF5 have been studied by means of 123Sb NQR spectra and spin-lattice relaxation measurements. The phase transitions occur at 117, 135 and 260 K. The line shape and temperature dependence of the spin-lattice relaxation time T1 at 135 to 260 K are characteristic for an incommensurate state with a plane wave modulation regime. At 117 to 135 K a distinct fine structure of the NQR spectra has been observed. The X-ray diffraction pattern of this phase is interpreted as a coexistence of two modulation waves along the a and b axis with wave vectors (a*/6 + b*/6) and (a*/2 + b*/2), respectively. The best interpretation that fits our NQR data is a coexistence of two domains, the structures of which are modulated with different periods in such a manner that each domain exhibits only one of the aforementioned modulation waves. Redistribution of line intensities with the variation of temperature shows that one of the domains becomes energetically preferable on cooling and is transformed into the low temperature phase at 117 K. The 123SbNQR measurements in K2SbF5 show unusually short values of T1, which become close to the spin-spin relaxation time T2 with increasing temperature. - Pacs: 61.44.Fw, 64.60, 64.70, 64.70.Rh, 76.60

A 35CL NQR Spin-Lattice Relaxation Study on the Motion of D4h Anions in [C(NH2)3]2PdCl4, [C(NH2)3]2PtCl4, and [C(NH2)3]AuCl4

1986 ◽  
Vol 41 (1-2) ◽  
pp. 416-420
Author(s):  
Yoshihiro Furukawa ◽  
Daiyu Nakamura
Keyword(s):  
Relaxation Times ◽  
Sharp Decrease ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Dependent ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
The One ◽  
Increasing Temperature ◽  
Complex Anions

The temperature dependence of 35Cl NQR spin-lattice relaxation times T1ClQ was observed for the crystal of the title complexes. For the Pd(II) and Pt(II) complexes, the log T1ClQ vs. 103 T-1 curves having gentle positive gradients at lower temperatures decreased sharply with increasing temperature from ca. 150 and ca. 130 K, respectively. This sharp decrease of T1ClQ can be explained by the C4 reorientation of the D4h complex anions with the activation energy Ea of 34 kJ mol-1 for the former and 29 kJ mol-1 for the latter complex. These values agree well with those estimated from 1H T1 showing temperature dependent dipolar-quadrupolar cross relaxation. For the Au(III) salt, two of four 35Cl NQR lines showed a sharp decrease in T1ClQ from ca. 270 K, suggesting the onset of the C4 reorientation of the one kind crystallographically equivalent anions with Ea of 67 kJ mol-1.

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