SPIN LATTICE RELAXATION IN NEODYMIUM ETHYLSULPHATE AT LIQUID HELIUM TEMPERATURES

1960 ◽  
Vol 38 (5) ◽  
pp. 604-615 ◽  
Author(s):  
J. M. Daniels ◽  
K. E. Rieckhoff
Keyword(s):  
Relaxation Time ◽  
Faraday Effect ◽  
Pulse Length ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Approach To Equilibrium ◽  
Spin Lattice ◽  
Spin Populations ◽  
Adiabatic Magnetization

The optical Faraday effect was used to measure instantaneous magnetization in neodymium ethylsulphate. The spin populations were disturbed by pulses of microwave power, and by adiabatic magnetization and demagnetization, and the approach to equilibrium was studied. The relaxation was found to be exponential and spin lattice relaxation times were measured, for temperatures between 1.3° K and 4.2° K, and for magnetic fields between 80 and 6000 oersted. The relaxation time was found to decrease with increasing magnetic field, and to vary with temperature approximately as 1/T3. No dependence of relaxation time on pulse length was found.

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.

RELAXATION IN RUBY

1960 ◽  
Vol 38 (10) ◽  
pp. 1304-1317 ◽  
Author(s):  
R. A. Armstrong ◽  
A. Szabo
Keyword(s):  
Relaxation Time ◽  
Crystal Orientation ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Cross Relaxation ◽  
Spin Lattice Relaxation ◽  
Signal Frequency ◽  
Spin Lattice ◽  
A Value ◽  
Frequency Ratios

The relaxation of the (1↔2) and (2↔3) transitions in chrome-doped Al2O3 (0.015%) has been studied at S-band, using a pulsed microwave method, over a range of crystal orientations in the magnetic field at temperatures of 77 deg;K to 50 deg;K, and at 4.2 deg;K and 1.6 deg;K. A T−7 variation of the relaxation time with temperature was found in the liquid nitrogen range. The relaxation time in this temperature range was found to be independent of crystal orientation, and for the (1↔2) transition was 50 microseconds at 77 deg;K. At liquid helium temperatures, harmonic cross relaxation was present over most of the range of the crystal orientation studied and was observed at harmonic-to-signal frequency ratios of 2:1, 3:2, and 1:2. The harmonic cross relaxation times were typically 10 to 100 times shorter than the lattice relaxation times, and were independent of temperature. At non-harmonic points at 4.2 deg;K, the spin–lattice relaxation could be described by one time constant, a value of 300 milliseconds being typical. At harmonic points anomalously long relaxation times as high as 12 seconds were observed.

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.

MEASUREMENT OF SPIN-LATTICE RELAXATION AT 890 Mc/s BY A RESONANCE-DISPERSION TECHNIQUE

1965 ◽  
Vol 43 (4) ◽  
pp. 576-593 ◽  
Author(s):  
J. A. Carruthers ◽  
N. C. Rumin
Keyword(s):  
Relaxation Time ◽  
Modulation Frequency ◽  
Power Level ◽  
Relaxation Times ◽  
Audio Signal ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Degree Of Saturation ◽  
Multiple Time ◽  
Spin Lattice

A new technique has been used to measure the spin-lattice relaxation time of Cr+++ in K3Co(CN)6 at 890 Mc/s. The method depends on observing both the amplitude and phase of the audio signal developed at the modulation frequency in a bridge-type microwave resonance spectrometer. One or more modulation frequencies are used, depending on the value of the relaxation time and the degree of saturation employed. Although similar to the saturation technique, this method does not require knowledge of the power level or the linewidth, and is suited to measurements on weak lines. Results have been obtained for lines at 100, 300, 1 400, and 2 100 oersteds, using crystals containing 0.06% and 0.4% chromium. The values of T1 for the lower concentration are in the 20–30-millisecond range, but relaxation appears to be not equivalent to a single time-constant. For the higher concentration the relaxation times are shorter and there is a marked evidence of multiple time-constants.

13C NMR Investigations on the Stacking of 5′ -AMP with Tryptamine

1977 ◽  
Vol 32 (5-6) ◽  
pp. 315-320 ◽  
Author(s):  
V. Wray ◽  
K. G. Wagner
Keyword(s):  
Particle Size ◽  
Relaxation Time ◽  
Complex Formation ◽  
Ring Current ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Adenosine Monophosphate ◽  
Spin Lattice Relaxation ◽  
Spin Lattice

Abstract Stacking, Relaxation Time, Tryptamine, 5′-Adenosine Monophosphate Complex formation between 5′-adenosine monophosphate (5′-AMP) and tryptamine was in­ vestigated by measuring 13C chemical shifts and spin-lattice relaxation times. The chemical shift changes observed were attributed to ring current effects originating in the stacking of the two respective aromatic moieties and to puckering changes of the AMP ribose. Differences in the magnitude of the shifts of the aromatic carbons were related to the geometry of the complex and compared with those found for AMP selfassociation. Upon complex formation the relaxation times of especially the tryptamine indole carbons were greatly reduced, this was explained by an in­ crease in the particle size. Small changes found for the AMP carbons in solutions without tryptamine result from AMP selfassociation. Deviations from isotropic motion observed for the non-aromatic moieties are discussed.

A Selective Determination of the Proton Nuclear Relaxation Times of the Alkaloid Vindoline

1972 ◽  
Vol 50 (4) ◽  
pp. 497-503 ◽  
Author(s):  
R. Burton ◽  
C. W. M. Grant ◽  
L. D. Hall
Keyword(s):  
Relaxation Time ◽  
Spin Relaxation ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Nuclear Relaxation ◽  
Methyl Group ◽  
Selective Determination ◽  
Spin Lattice

An audiofrequency-pulse n.m.r. spectrometer has been used to measure the nuclear relaxation times of individual protons of the alkaloid, vindoline. For this substance in deuterochloroform solution the spin–lattice relaxation times (T1) vary between 1.15 and 1.50 s and the spin–spin relaxation times (T2) are between 0.90 and 1.40 s. The N-methyl group has the shortest relaxation time of those resonances which were measured. A discussion of the apparatus and methodology is given.

Conductivity Vs Nmr Correlation Times, and Decoupled Cation Motion in Polymer-In-Salt Electrolytes

1992 ◽  
Vol 293 ◽  
Author(s):  
Jiang Fan ◽  
R.F. Marzke ◽  
C.A. Angeill
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Conductivity Relaxation ◽  
Spin Lattice ◽  
Low Salt ◽  
Cation Matrix ◽  
Pure Salt ◽  
Conductivity Relaxation Time

AbstractWe report 7Li spin lattice relaxation times at 12.82 MHz over a range of temperatures for liquid electrolytes of various salt:polymer ratios, and compare the NMR correlation time obtained at the temperature of the T1 minimum with the conductivity relaxation time at the same temperature. We find that at low salt contents the two relaxation times have the same value, but beyond the “salt-inpolymer to polymer-in-salt transition” zone at the Tg maximum, the two times increasingly separate. This is taken as evidence for the onset of cation-matrix mobility decoupling, which maximizes at the pure salt extreme.

Spin–lattice relaxation of Fe3+ in rutile for X- and F-band transitions

1969 ◽  
Vol 47 (15) ◽  
pp. 1573-1583 ◽  
Author(s):  
G. J. Lichtenberger
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
Transition Probabilities ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Rate Equations ◽  
Relaxation Rates ◽  
Time Resolved ◽  
Spin Lattice

Detailed measurements of the angular and temperature dependence (1.6 °K to 4.2 °K) of the dominant spin–lattice relaxation rates of Fe3+ in rutile have been carried out for a number of strong transitions at 9.4 Gc and 121 Gc using the pulse saturation method. At 9.4 Gc, two relaxation time components were observed, ranging from 0.5 to 1.2 ms and 1.6 to 4.0 ms, respectively, at 4.2 °K. Assuming a relationship of the form log(relaxation time) = −n∙log(temperature), the temperature dependence factor n was found to be between 0.4 and 1.0. The single relaxation time resolved at F band had values from 0.7 to 1.0 ms at 4.2 °K, and n between 0.1 and 0.6. The corresponding relative relaxation rates were calculated from the direct process spin–phonon transition probabilities, assuming Debye elastic isotropy for rutile. Using a cubic spin–lattice coupling tensor, [Formula: see text] was found to be 0.5 and the rate equations for the six-level system were solved. The calculated effective relaxation times were successfully identified with the slower dominant relaxation component of the experimental data.

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