13C and 2H spin–lattice relaxation in solid adamantane

1980 ◽  
Vol 58 (7) ◽  
pp. 655-657 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Brian A. Pettitt
Keyword(s):  
Angular Correlation ◽  
Transition Point ◽  
Relaxation Times ◽  
Proton Nmr ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nmr Data ◽  
Plastic Phase ◽  
Good Agreement

Spin–lattice relaxation times for the 13C nuclei of adamantane and the 2H nuclei of adamantane-d16 are reported for most of the temperature range of the solid I (plastic) phase, and for the solid II phase just below the transition point. Angular correlation times are shown to be in good agreement with those previously obtained from proton nmr data by Resing.

A133Cs NMR Spin-Lattice Relaxation Study in Incommensurate Cs2CdI4

2000 ◽  
Vol 55 (1-2) ◽  
pp. 339-342 ◽  
Author(s):  
Koh-ichi Suzuki ◽  
Shin'ichi Ishimaru ◽  
Ryuichi Ikeda
Keyword(s):  
Critical Exponent ◽  
Relaxation Times ◽  
Three Dimensional ◽  
Lattice Relaxation ◽  
Normal Phase ◽  
Incommensurate Phase ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Relaxation Study ◽  
Good Agreement

133Cs NMR spin-lattice relaxation times(T1) in crystalline Cs2CdI4 were measured at 225 - 373 K. The critical exponent ( of T\ observed near the normal-incommensurate transition in the normal phase was determined to be 0.62 ± 0.03, in good agreement with the predicted value for three-dimensional XK-model. The frequency dependent T1 in the incommensurate phase could be explained by the fluctuation of amplitudon and small gap phason.

scholarly journals 15N and 133Cs Solid NMR Studies on Ionic Dynamics in Plastic CsNO2

1996 ◽  
Vol 51 (5-6) ◽  
pp. 761-768 ◽  
Author(s):  
H. Honda ◽  
M. Kenmotsu ◽  
N. Onoda-Yamamuro ◽  
H. Ohki ◽  
S. Ishimaru ◽  
...  
Keyword(s):  
Phase Ii ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Nmr Studies ◽  
Self Diffusion ◽  
Spin Lattice ◽  
Solid Nmr ◽  
Plastic Phase

The temperature dependence of the 15N and 133Cs NMR spin-lattice relaxation times, the 15N spin-spin relaxation time, and the 15N and 133Cs spectra of CsNO2 was observed in the plastic phase (209.2 < T < 673 K (m. p.)) and the low-temperature phase (Phase II). In Phase II we found the NO-2 180°-flip, which could be attributed to the anomalous increase of the heat capacity curve, and determined the activation energy of this motion to be 8.7-11.7 kJ mol-1. The 15N and 133Cs spectra in this phase are inconsistent with the reported crystal structure R3̅m and can be explained by lower crystal symmetry. In the plastic phase we detected a new anionic motion with 11 kJ mol-1 , an isotropic NO-2 reorientation with 8.5-9 kJ mol-1, and ionic self-diffusion with 47 kJ mol-1. The presence of ionic self-diffusion was confirmed by measuring the electrical conductivity.

Intermolecular potentials from NMR data: H2–N2O and H2–CO2

1983 ◽  
Vol 61 (5) ◽  
pp. 664-670 ◽  
Author(s):  
Lakshman Pandey ◽  
C. P. K. Reddy ◽  
K. Lalita Sarkar
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Intermolecular Potential ◽  
Quadrupole Moments ◽  
Spin Lattice ◽  
Lennard Jones ◽  
Nmr Data ◽  
Potential Parameters

Proton spin-lattice relaxation times T1 were measured in mixtures of H2 with N2O as a function of density, composition, and temperature (200–400 K) in the region where [Formula: see text]. These data, along with the data obtained by Lalita and Bloom for H2–CO2, were interpreted, using Bloom–Oppenheim theory, to obtain the anisotropic intermoleeular potential parameters. Two models, (i) the Lennard–Jones (12–6) potential (LJP) and (ii) the modified Buckingham (exp-6) potential (MBP), were used to represent the isotropic part of the intermolecular potential. The relative anisotropy in the attractive r−6 term and the quadrupole moments of N2O and CO2 as obtained from MBP model are in better agreement with the values obtained from the polarizability data and the reported values, respectively, than those obtained from the LJP model.

scholarly journals Comparison of Structure and Local Dynamics of Two Peptide Dendrimers with the Same Backbone but with Different Side Groups in Their Spacers

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1657 ◽  
Author(s):  
Sofia Mikhtaniuk ◽  
Valeriy Bezrodnyi ◽  
Oleg Shavykin ◽  
Igor Neelov ◽  
Nadezhda Sheveleva ◽  
...  
Keyword(s):  
Ion Pairs ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Peptide Dendrimers ◽  
Wide Range ◽  
Dynamics Method ◽  
Perform Computer Simulation ◽  
Good Agreement

In this paper, we perform computer simulation of two lysine-based dendrimers with Lys-2Lys and Lys-2Gly repeating units. These dendrimers were recently studied experimentally by NMR (Sci. Reports, 2018, 8, 8916) and tested as carriers for gene delivery (Bioorg. Chem., 2020, 95, 103504). Simulation was performed by molecular dynamics method in a wide range of temperatures. We have shown that the Lys-2Lys dendrimer has a larger size but smaller fluctuations as well as lower internal density in comparison with the Lys-2Gly dendrimer. The Lys-2Lys dendrimer has larger charge but counterions form more ion pairs with its NH 3 + groups and reduce the bare charge and zeta potential of the first dendrimer more strongly. It was demonstrated that these differences between dendrimers are due to the lower flexibility and the larger charge (+2) of each 2Lys spacers in comparison with 2Gly ones. The terminal CH2 groups in both dendrimers move faster than the inner CH2 groups. The calculated temperature dependencies of the spin-lattice relaxation times of these groups for both dendrimers are in a good agreement with the experimental results obtained by NMR.

NH4+ Ion Motions in Some Ammonium Salts

1981 ◽  
Vol 36 (3) ◽  
pp. 205-209 ◽  
Author(s):  
Fevzi Köksal
Keyword(s):  
Hydrogen Bonding ◽  
Low Temperatures ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Experimental Results ◽  
Ammonium Salts ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Unit Cells ◽  
Good Agreement

Spin-lattice relaxation times of protons in polycrystalline (NH4)2SO4, (NH3OH)2SO4, (NH4)2HPO4, NH4VO3, (NH4)2CrO4, (NH4)2C2O4 • H2O and NH4HF2 salts were measured over the temperature range 100-430 K. The double minima in T1 for the first three compounds were attributed to the nonequivalent NH4+ ions in the unit cells. In NH4VO3, the double minima were attributed to the reorientations about two and three fold axes. However only one minimum in T1 was observed for (NH4)2CrO4, (NH4)2C2O4 • H2O and NH4HF2 and the relaxation mechanisms for the first three compounds were attributed to random reorientations of NH4+ ions. The experimental results are in good agreement with the calculated values by using the existing theoretical expressions. The discrepancies between experimental and calculated values for (NH4)2HPO4 and NH4HF2 at low temperatures were attributed to the tightness of the hydrogen bonding at those temperatures

Self-Diffusion in the Ionic Plastic Phase of (CH3 )3 NHClO4 Studied by 1H NMR and Electrical Conductivity

1996 ◽  
Vol 51 (1-2) ◽  
pp. 83-86
Author(s):  
Hiroyuki Ishida ◽  
Yoshihiro Furukawa
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Spin Relaxation ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Self Diffusion ◽  
Spin Lattice ◽  
H Nmr ◽  
Plastic Phase

Abstract Spin-lattice relaxation times (T1) and spin-spin relaxation times (T2) of 1H NMR and the electrical conductivity (σ) of trimethylammonium perchlorate were measured in the ionic plastic phase obtainable above 480 K. In this phase, both the cation and anion were revealed to perform self-diffusion. The activation energy (Ea ) of the cationic diffusion was evaluated to be 55 ± 4 and 50 ± 4 kJ mol-1 from 1H T1 and 1H T2 respectively, while Ea of the anionic diffusion was 64 ±3 kJ mol-1 from the electrical conductivity.

Proton NMR Spin-Lattice Relaxation Time Characterization of a-Si(H) Structure

1980 ◽  
Vol 3 ◽  
Author(s):  
M. E. Lowry ◽  
R. G. Barnes ◽  
D. R. Torgeson ◽  
F. R. Jeffrey
Keyword(s):  
Relaxation Time ◽  
Room Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Mixed Phase ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nmr Data

ABSTRACTNMR data are presented for reactively sputtered amorphous silicon-hydrogen alloys (a-Si(H)). Measured differences in two of the samples are attributed to two distinct morphologies: a mixed phase (monohydride and dihydride) and a purely monohydride composition. Features of the mixed phase morphology have been modeled. Room temperature, 35 MHz spin-lattice relaxation times are presented for a series of monohydride samples prepared with systematically varied sputtering parameters. A correlation of proton T1 with the density of ESR states tentatively is suggested.

NQR and NMR Studies of Phase Transitions in R2Pb[Cu(NO2)6] (R = K, Rb, Tl, Cs, and NH4)

1996 ◽  
Vol 51 (5-6) ◽  
pp. 721-725
Author(s):  
Motohiro Mizuno ◽  
Tetsuo Asaji ◽  
Masahiko Suhara ◽  
Yoshihiro Furukawa
Keyword(s):  
Transition Point ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Incommensurate Phase ◽  
The Other ◽  
Spin Lattice Relaxation ◽  
Nmr Studies ◽  
Spin Lattice ◽  
H Nmr ◽  
The Difference

Abstract39K, 87, 85Rb, 133Cs, 205T1, and 1, 2H NMR spin-lattice relaxation times T1 and 14N NQR spin-lattice relaxation times T1Q were determined for R2Pb[Cu(NO2)6] (R = K, Rb, Tl, Cs, and NH4). T1 of 39K and 87Rb showed very short values in the incommensurate phase as compared with those in the other phases. When the commensurate-incommensurate phase transition point is approached from below, 14N T1Q of the R = K, Rb, Tl, and NH4 compounds showed rapid decrease. On the other hand, that of the R = Cs compound began to decrease first after passing beyond the corresponding transition point. The difference of the T1Q behavior may be ascribed to the difference of the condensed phonon mode in the incommensurate phase.

35Cl NQR in Glassy Crystal of 2-chlorothiophene

2000 ◽  
Vol 55 (1-2) ◽  
pp. 183-185 ◽  
Author(s):  
Hiroki Fujimori ◽  
Tetsuo Asaji
Keyword(s):  
Activation Energy ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Half Maximum ◽  
Glass Transitions ◽  
Spin Lattice ◽  
Calorimetric Measurements ◽  
35Cl Nqr ◽  
Good Agreement

Stable crystalline 2-chlorothiophene has two glass transitions at 164 and 186 K. 35CI NQR measurements were carried out between 77 and 200 K. Two NQR signals with full widths of about 100 kHz at half maximum were observed in this temperature range. The spin-lattice relaxation times T1 were measured at the two peak frequencies. The activation energy obtained from the results of the T1 measurements showed a fairly good agreement with those estimated from calorimetric measurements.

Molecular Motion and Crystal Structure of Solid Tetrapentylammonium Iodide

2000 ◽  
Vol 55 (8) ◽  
pp. 706-710 ◽  
Author(s):  
B. Szafrańska ◽  
H. Małuszyńska ◽  
Z. Pająk
Keyword(s):  
Crystal Structure ◽  
Solid Phase ◽  
Relaxation Times ◽  
Activation Parameters ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Spin Lattice ◽  
Plastic Phase

Abstract The proton NMR spectra and spin-lattice relaxation times of tetrapentylammonium iodide have been measured between 100 K and the melting point. The room temperature crystal structure has been determined by X-ray diffraction as orthorhombic, space group Ccca, Z = 4 with a = 10.811(2), b = 22.771(5) and c = 9.500(2) Å with fully ordered tetrapentylammonium cations. The existence of a solid-solid phase transition at 400 K has been confirmed by DTA. The onset of C 3 methyl group reorientations characterized by Arrhenius activation parameters has been evidenced. The intracation conformational motions in the pentyl chains start to manifest themselves already at lower temperatures. The appearence of an ionic plastic phase with coexisting liquid-like and solid-like cations has been discovered.

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