Nuclear relaxation in solid paramagnets at very low temperatures

1996 ◽  
Vol 46 (S4) ◽  
pp. 2223-2224
Author(s):  
Levan L. Buishvili ◽  
Nikolai P. Giorgadze ◽  
Nathalie P. Fokina
Keyword(s):  
Low Temperatures ◽  
Nuclear Relaxation

Nuclear relaxation ofF19in RbMnF3at very low temperatures

1976 ◽  
Vol 14 (11) ◽  
pp. 4826-4829 ◽  
Author(s):  
M. Twerdochlib ◽  
E. R. Hunt
Keyword(s):  
Low Temperatures ◽  
Nuclear Relaxation

Nuclear Relaxation in SolidHe3at Low Temperatures

1967 ◽  
Vol 163 (1) ◽  
pp. 181-185 ◽  
Author(s):  
E. R. Hunt ◽  
R. C. Richardson ◽  
J. R. Thompson ◽  
R. A. Guyer ◽  
Horst Meyer
Keyword(s):  
Low Temperatures ◽  
Nuclear Relaxation

The two-level systems role in nuclear relaxation at low temperatures

1991 ◽  
Vol 168 (3) ◽  
pp. 205-210 ◽  
Author(s):  
L.L. Buishvili ◽  
L.Zh. Zakharov ◽  
A.I. Tugushi ◽  
N.P. Fokina
Keyword(s):  
Low Temperatures ◽  
Nuclear Relaxation ◽  
Two Level Systems

Attempts to increase the nuclear relaxation time of a3He gas at low temperatures

1988 ◽  
Vol 72 (1-2) ◽  
pp. 165-188 ◽  
Author(s):  
Val�rie Lefevre-Seguin ◽  
Jean Brossel
Keyword(s):  
Relaxation Time ◽  
Low Temperatures ◽  
Nuclear Relaxation

Nuclear magnetic resonance at low temperatures

1949 ◽  
Vol 199 (1057) ◽  
pp. 222-237 ◽  
Keyword(s):  
Nuclear Spin ◽  
Low Temperatures ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Nuclear Relaxation ◽  
Spin Lattice ◽  
Paramagnetic Impurities ◽  
Nuclear Spin Lattice Relaxation ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

Investigations have been made on nuclear paramagnetism at low temperatures by the radiofrequency resonance absorption method. In measurements on solid hydrogen it has been found that there are considerable changes in the width of the resonance line with change of temperature. These effects are related to changes in the nature of the molecular motions and the state of the molecular order. A number of experiments have been made on nuclear spin-lattice relaxation in different substances. It has been shown that in ionic crystals the nuclear relaxation is greatly affected by the presence of paramagnetic impurities. The nuclear relaxation time in metals has been found to be in reasonable agreement with theoretical predictions. Measurements have been extended to temperatures below 1 ° K, and the possibility of cooling the nuclear spin system by adiabatic demagnetization has been verified. The results for nuclear spin-lattice relaxation are considered in relation to the possible applications of nuclear paramagnetism in the region of very low temperatures.

Nuclear Relaxation in Solids due to Molecular Rotation at Low Temperatures

1970 ◽  
Vol 52 (5) ◽  
pp. 2534-2538 ◽  
Author(s):  
Daniel Wallach ◽  
William A. Steele
Keyword(s):  
Low Temperatures ◽  
Molecular Rotation ◽  
Nuclear Relaxation

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Radiation Damage of Support Films

1981 ◽  
Vol 39 ◽  
pp. 28-29
Author(s):  
H.A. Cohen ◽  
W. Chiu
Keyword(s):  
Transfer Function ◽  
Low Temperatures ◽  
Carbon Support ◽  
Contrast Transfer Function ◽  
Electron Dose ◽  
Imaging Parameters ◽  
Negative Stain ◽  
Phase Corrections ◽  
Two Parameters ◽  
Medium Dose

The goal of imaging the finest detail possible in biological specimens leads to contradictory requirements for the choice of an electron dose. The dose should be as low as possible to minimize object damage, yet as high as possible to optimize image statistics. For specimens that are protected by low temperatures or for which the low resolution associated with negative stain is acceptable, the first condition may be partially relaxed, allowing the use of (for example) 6 to 10 e/Å2. However, this medium dose is marginal for obtaining the contrast transfer function (CTF) of the microscope, which is necessary to allow phase corrections to the image. We have explored two parameters that affect the CTF under medium dose conditions.Figure 1 displays the CTF for carbon (C, row 1) and triafol plus carbon (T+C, row 2). For any column, the images to which the CTF correspond were from a carbon covered hole (C) and the adjacent triafol plus carbon support film (T+C), both recorded on the same micrograph; therefore the imaging parameters of defocus, illumination angle, and electron statistics were identical.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

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