Quadrupolar Relaxation of X Type Nuclei in R2MX6 and RMX3 Compounds

1975 ◽  
Vol 53 (12) ◽  
pp. 1141-1147 ◽  
Author(s):  
Henry M. van Driel ◽  
Robin L. Armstrong
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Mode Spectrum ◽  
Spin Lattice ◽  
Raman Process ◽  
Quadrupole Resonance ◽  
Quadrupolar Relaxation

Calculations of nuclear quadrupolar spin–lattice relaxation times are presented. The expressions obtained for the first order Raman and anharmonic Raman processes are applicable to a pure nuclear quadrupole resonance investigation of the X nuclei in R2MX6 and RMX3 solids. On the basis of realistic assumptions it is shown that the anharmonic Raman process will provide the dominant relaxation mechanism for these nuclei in these compounds. The relation between the spin–lattice relaxation time and the lattice dynamics is obtained explicitly without recourse to an assumed form of lattice vibrational normal mode spectrum. In favorable cases it is shown that the spin–lattice relaxation times can be related to Brillouin zone averaged rotary mode frequencies which are useful for the analysis of experimental data.

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.

Relaxation of 121Sb NQR in Antimony Trichloride due to Raman Process

2001 ◽  
Vol 56 (11) ◽  
pp. 777-784 ◽  
Author(s):  
Noriaki Okubo ◽  
Mutsuo Igarashi
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Antimony Trichloride ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Abstract The spin-lattice relaxation times of 121Sb nuclear quadrupole resonance in SbCl3 have been measured from 4.2 K to the m. p., 346 K. The result is analyzed with a theory of the Raman process based on co­ valency and discussed in comparison with the previous result for Cl nuclei.

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.

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.

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.

35Cl NQR Studies of Bismuth Trichloride

1997 ◽  
Vol 52 (8-9) ◽  
pp. 614-620
Author(s):  
P. K. Babu ◽  
J. Ramakrishna
Keyword(s):  
Temperature Dependence ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Positive Temperature Coefficient ◽  
Spin Lattice Relaxation ◽  
Positive Temperature ◽  
Lattice Vibrations ◽  
Spin Lattice ◽  
Quadrupole Resonance ◽  
35Cl Nqr

Abstract The temperature dependence of the 35Cl nuclear quadrupole resonance (NQR) frequency and spin lattice relaxation time (T1) are studied in crystalline BiCl3 , in the range 40-300 K. The positive temperature coefficient observed for one of the 35Cl resonances is explained in terms of the strong intermolecular interactions that exist in this compound. Variation of with temperature is found to be similar at the chemically inequivalent halogen sites. Semiclassical descriptions based on torsional oscillator dynamics are found to be inadequate for explaining the spin lattice relaxation. T1 (T) data follow an AT2 + BT3 type behaviour, indicating that the anharmonic nature of the lattice vibrations plays a significant role in determining the temperature dependence of T1 at high temperatures.

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.

Spin–lattice relaxation of 1,2-dichloroethane in different solvents

1969 ◽  
Vol 47 (24) ◽  
pp. 4635-4638 ◽  
Author(s):  
E. Bock ◽  
E. Tomchuk
Keyword(s):  
Relaxation Rate ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Weakly Magnetic ◽  
Solvent Molecules ◽  
The Individual ◽  
Deuterated Benzene

The spin–lattice relaxation time of the 1,2-dichloroethane molecule has been determined in 6 different nonmagnetic or weakly magnetic solvents at 20 °C, viz: deuterated benzene, carbon disulfide, deuterated 1,2-dichloroethane, carbon tetrachloride, and deuterated chloroform. From the experimental results the relaxation rate in infinitely dilute solution, the so called intramolecular relaxation rate, was determined for each solvent. It was found that the observed intramolecular relaxation rate could be successfully interpreted as arising solely from a dipole–dipole relaxation mechanism. It was further found that the individual differences in the value of the intramolecular spin–lattice relaxation rate of the 1,2-dichloroethane molecule in different solvents could be accounted for in terms of weak complex formation between the solute and solvent molecules.

scholarly journals Possibilities of proton magnetic resonance in determination the cellulose crystallinity

2019 ◽  
Vol 59 (8) ◽  
pp. 116-123
Author(s):  
Yury B. Grunin ◽  
◽  
Maria S. Ivanova ◽  
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Active Surface ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Cellulose Crystallinity ◽  
Spin Lattice ◽  
Free Induction

A layered model of the structural organization of macrofibrils of native cellulose, consisting of microfibrils, which include elementary fibrils, has been developed. A feature of the proposed model is the presence of slit-like pores between the crystalline elements of cellulose. It was found that, on average, each water molecule interacts with one glucose residue of the surface chains of cellulose with the formation of hydrogen bonds in the framework of monolayer adsorption. This allows to establish a correlation between the cellulose crystallinity and the capacity of the adsorption water monolayer on its active surface. Based on the condition of rapid molecular exchange between the adsorption water layers in the framework of the Bloembergen-Purcell-Pound theory, an approach is proposed for determination the capacity of water monolayer. The obtained values are consistent with the results of solving the Brunauer-Emmett-Teller equation for the adsorption isotherm of water on the active surface of cellulose. The Fourier transform of the free induction decay signal of cellulose allows to estimate its crystallinity at various moisture contents. Methods have been developed for assessing the crystallinity of different types of dry cellulose based on NMR relaxation parameters — spin-lattice relaxation time and spin-spin relaxation time. Using the method of deuteration of cellulose, the relaxation times of its crystalline regions were determined. The results of preliminary studies showed that the crystallinity of cotton cellulose is higher in comparison with the same parameter of woody types of cellulose. A comparison of the literature and the data we obtained using 1H-NMR relaxation confirmed the possibility of utilizing the developed methods to solve the tasks of scientific research and conducting quality control of cellulosic materials at specialized enterprises.

scholarly journals Spin-Gitter-Relaxationszeit T1 von Nitrilkohlenstoffen / Spin-Lattice-Relaxation Time T1 of Nitrile Carbon-atoms

1979 ◽  
Vol 34 (3) ◽  
pp. 375-379 ◽  
Author(s):  
H. Sterk ◽  
J. Kalcher ◽  
G. Kollenz ◽  
H. Waldenberger
Keyword(s):  
Relaxation Time ◽  
Correlation Time ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Rotation ◽  
Spin Lattice Relaxation ◽  
Hydrogen Atoms ◽  
Spin Lattice ◽  
Almost All

Abstract It is shown that in almost all nitrile carbon-atoms T1 depends first of all on the inter-and/or intramolecular dipol-dipol-relaxation mechanism. Only acetonitrile, as is already known, shows a remarkable dependence on the spin-rotation-relaxation mechanism. This influence is strongly decreasing with an increasing number of atoms, specially hydrogen atoms, in the molecule. The significance of the correlation time r is discussed extensively and the experimental results are verified by calculation of T1 using the viscosity and the inertial moments as parameters.

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