A nuclear magnetic resonance relaxation study of liquid hydrogen cyanide

1987 ◽  
Vol 65 (9) ◽  
pp. 2077-2081 ◽  
Author(s):  
Roderick E. Wasylishen
Keyword(s):  
Temperature Dependence ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Correlation Times ◽  
Spin Lattice ◽  
Quadrupolar Coupling ◽  
Quadrupolar Relaxation ◽  
Resonance Relaxation

The rates of 2H, 13C, and 14N spin-lattice relaxation for liquid deuterium cyanide have been studied as a function of temperature. The quadrupolar nuclei relax exclusively by the quadrupolar relaxation mechanism while the rate of 13C and 15N relaxation is completely dominated by the spin-rotation mechanism. The apparent activation energy that describes the temperature dependence of spin-lattice relaxation for all nuclei studied is approximately 1.6 kcal mol−1. The temperature dependence of the rate of 13C relaxation in liquid HCN was also investigated. Although the determination of very accurate rotational and angular momentum correlation times is hampered by intermolecular effects on the nuclear quadrupolar coupling constants and the appropriately averaged C—H bond separation, the derived correlation times for DCN and HCN are in reasonable agreement (± 15%).

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.

scholarly journals Temperature dependence of the Spin-Lattice Relaxation Time of the 23Na-NMR Line in NaNO2

1992 ◽  
Vol 47 (1-2) ◽  
pp. 313-318 ◽  
Author(s):  
M. Igarashi ◽  
H. Kitagawa ◽  
S. Takahashi ◽  
R. Yoshizaki ◽  
Y. Abe
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
Lattice Relaxation ◽  
Polycrystalline Sample ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice Relaxation Time ◽  
Spin Lattice ◽  
23Na Nmr

AbstractThe spin-lattice relaxation time, T1, of the 23Na-NMR line in NaNO2 is measured between 25 K and 160 K at two magnetic field strengths, 1.1 T and 6.9 T. The temperature dependence of T1 for the center line, observed on a polycrystalline sample prepared by precipitation from aqueous solution, is given by a monotonous curve. T1 increases gradually as the temperature decreases. On the other hand for a single crystal, which is made by a modified Bridgman method, the temperature dependence of T1 shows two deep dips below 150 K and a frequency dependence which cannot be explained by ordinary BPP theory. The dominant relaxation mechanism above and below 150 K is also investigated.

Boron-11, boron-10, and nitrogen-14 NMR relaxation rates and quadrupole coupling constants in BH3NH3

1992 ◽  
Vol 70 (9) ◽  
pp. 2420-2423 ◽  
Author(s):  
Glenn H. Penner ◽  
Stephen I. Daleman ◽  
Angela R. Custodio
Keyword(s):  
Relaxation Times ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Orbital Theory ◽  
Spin Lattice ◽  
Quadrupolar Coupling ◽  
Field Gradients

The 11B, 10B, and 14N spin–lattice relaxation times (T1) for aqueous solutions of BH3NH3 were measured by NMR spectroscopy. The results of this investigation are consistent with the nuclear quadrupolar coupling constants reported in previous nuclear quadrupolar resonance and microwave studies. The activation energy associated with rotational reorientation of BH3NH3 in aqueous solution is 11.7 ± 0.6 kJ/mol. Electric field gradients were calculated at various levels of abinitio molecular orbital theory, in order to obtain theoretical 14N and 11B quadrupolar coupling constants. At the highest level of calculation (CI(SD)/6-31G**//MP2/6-31G**), these are in agreement with recently reported microwave results but not with previously reported NQR experiments.

Deuterium Nuclear Spin–Lattice Relaxation Times and Quadrupolar Coupling Constants in Isotopically Labeled Saccharides

2000 ◽  
Vol 144 (2) ◽  
pp. 207-216 ◽  
Author(s):  
Bidisha Bose-Basu ◽  
Jaroslav Zajicek ◽  
Gail Bondo ◽  
Shikai Zhao ◽  
Meredith Kubsch ◽  
...  
Keyword(s):  
Nuclear Spin ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Quadrupolar Coupling ◽  
Nuclear Spin Lattice Relaxation

Bonded Hydrogen and Trapped H2 in a-Si1−xGex:H Alloys

1989 ◽  
Vol 149 ◽  
Author(s):  
E. J. Vanderheiden ◽  
G. A. Williams ◽  
P. C. Taylor ◽  
F. Finger ◽  
W. Fuhs
Keyword(s):  
Temperature Dependence ◽  
Molecular Hydrogen ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
H Nmr ◽  
Local Environments

ABSTRACT1H NMR has been employed to study the local environments of bonded hydrogen and trapped molecular hydrogen (H2) in a series of a-Si1−xGex:H alloys. There is a monotonic decrease of bonded hydrogen with increasing x from ≈ 10 at. % at x = 0 (a-Si:H) to ≈ 1 at. % at x = 1 (a-Ge:H). The amplitude of the broad 1H NMR line, which is attributed to clustered bonded hydrogen, decreases continuously across the system. The amplitude of the narrow 1H NMR line, which is attributed to bonded hydrogen essentially randomly distributed in the films, decreases as x increases from 0 to ≈ 0.2. From x = 0.2 to x ≈ 0.6 the amplitude of the narrow 1H NMR line is essentially constant, and for x ≥ 0.6 the amplitude decreases once again. The existence of trapped H2 molecules is inferred indirectly by their influence on the temperature dependence of the spin-lattice relaxation times, T1. Through T1, measurements it is determined that the trapped H2 concentration drops precipitously between x = 0.1 and x = 0.2, but is fairly constant for 0.2 ≤ x ≤ 0.6. For a-Si:H (x = 0) the H2 concentration is ≈ 0.1 at. %, while for x ≥ 0.2 the concentration of H2 is ≤ 0.02 at. %.

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