Measurements of correlation times by means of the temperature dependence of coherent pulse averaging effects in NMR

1971 ◽  
Vol 34 (3) ◽  
pp. 162-163 ◽  
Author(s):  
H. Schmiedel ◽  
D. Freude ◽  
W. Gründer
Keyword(s):  
Temperature Dependence ◽  
Correlation Times ◽  
Coherent Pulse

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%).

Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

1982 ◽  
Vol 40 ◽  
pp. 78-79
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Fatty Acid ◽  
Inelastic Scattering ◽  
Temperature Dependence ◽  
Structural Damage ◽  
Direct Result ◽  
Second Step ◽  
Strong Temperature Dependence ◽  
Electron Dose ◽  
Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

Temperature Dependence of Magnetic Domains and Wall Structures

1972 ◽  
Vol 30 ◽  
pp. 496-497
Author(s):  
Sonoko Tsukahara ◽  
Tadami Taoka ◽  
Hisao Nishizawa
Keyword(s):  
Temperature Dependence ◽  
Domain Walls ◽  
Magnetic Domain ◽  
Iron Film ◽  
Objective Lens ◽  
Lorentz Microscopy ◽  
Domain Structures ◽  
Wall Structures ◽  
Crystal Films ◽  
Metallurgical Structure

The high voltage Lorentz microscopy was successfully used to observe changes with temperature; of domain structures and metallurgical structures in an iron film set on the hot stage combined with a goniometer. The microscope used was the JEM-1000 EM which was operated with the objective lens current cut off to eliminate the magnetic field in the specimen position. Single crystal films with an (001) plane were prepared by the epitaxial growth of evaporated iron on a cleaved (001) plane of a rocksalt substrate. They had a uniform thickness from 1000 to 7000 Å.The figure shows the temperature dependence of magnetic domain structure with its corresponding deflection pattern and metallurgical structure observed in a 4500 Å iron film. In general, with increase of temperature, the straight domain walls decrease in their width (at 400°C), curve in an iregular shape (600°C) and then vanish (790°C). The ripple structures with cross-tie walls are observed below the Curie temperature.

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