Zur Protonenrelaxation von Wasser an Silikagelen

1967 ◽  
Vol 22 (11) ◽  
pp. 1751-1760 ◽  
Author(s):  
D. Michel
Keyword(s):  
Water Clusters ◽  
Relaxation Times ◽  
Dipolar Interaction ◽  
Relaxation Mechanism ◽  
Silica Gels ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Proton Proton ◽  
Adsorbed Molecules ◽  
Paramagnetic Impurities

In most cases the proton relaxation of adsorbed liquids and gases is caused by the proton-proton dipolar interaction and the coupling between protons and paramagnetic impurities (e. g. Fe3+-ions) of the adsorbent. The latter relaxation mechanism, however, has been neglected up till now although in some commercial silica gels it’s contribution can be the most important one (see Section 2.2). Consequently, motional phenomena of adsorbed molecules can only be studied by NMR techniques if the relative largeness of these two relaxation rates has been estimated, as can be done by investigating the dependence of proton relaxation-times on the H/D-ratio. Relaxation-time measurements in the temperature range from —100° to +80°C indicate that proton transfers occur between surface hydroxils and adsorbed particles. In a sample of 3/4 statistical monolayer the presence of two different types of water, clusters containing 95% of the adsorbed molecules with correlation time τc2=2.7 · 10-10 s (0°C), and more individually adsorbed particles with τc1 ⪆ 2.3 ·10-8 (0°C), has been inferred (see Section 2.1).

Protonenspinrelaxation von Benzol an Silikageloberflächen

1968 ◽  
Vol 23 (3) ◽  
pp. 339-347
Author(s):  
D. Michel
Keyword(s):  
Temperature Dependence ◽  
Magnetic Relaxation ◽  
Spin Echo ◽  
Relaxation Times ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Proton Proton ◽  
Proton Interaction ◽  
Paramagnetic Impurities ◽  
Hydroxyl Protons

Using spin-echo-techniques the temperature dependence of the proton magnetic relaxation times T1 and T2 of adsorbed benzene has been measured in the interval between +70 °C and —140 °C. Normal benzene C6H6 and mixtures of benzene and C6D6e were adsorbed on two sorts of silicagels which have been described elsewhere 4,9.The effective nuclear magnetic relaxation rates of adsorbed benzene are given by four contributions: the intramolecular proton-proton interaction, the interaction between benzene protons and paramagnetic impurities of the adsorbents, the interaction between benzene protons and hydroxyl protons on the silicagel surface, and the intermolecular interaction between benzene protons. These proton relaxation mechanisms depend differently on the H/D-ratio in C6H6—C6D6 mixtures (see section 4.1).The temperature dependence of the contributions 1/T1 intra and 1/T2 intra due to intramolecular proton-proton interaction suggests an anisotropic rotation of benzene molecules on the gel used. Furthermore, the existence of three different regions for the adsorbed benzene molecules has been inferred (see sections 4.2 and 5).

Molecular Reorientation of Methanol in Mixtures with Carbon Tetrachloride

1992 ◽  
Vol 47 (7-8) ◽  
pp. 857-864 ◽  
Author(s):  
M. D. Zeidler ◽  
D. S. Gill ◽  
M. D. Zeidler
Keyword(s):  
Carbon Tetrachloride ◽  
Composition Dependence ◽  
Nmr Relaxation ◽  
Dipolar Interaction ◽  
Coupling Constants ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Molecular Reorientation ◽  
Quadrupole Coupling ◽  
Interaction Contribution

Abstract Proton and oxygen-17 nmr relaxation rates of CD317OH as well as deuteron nmr relaxation rates of CH3OD were measured in mixtures with carbon tetrachloride at different compositions and temperatures. By varying the 170-content different contributions to the proton relaxation rate could be separated and from the 17O-H dipolar interaction contribution the correlation time τ2OH of the OH bond was determined. Using these correlation times the composition dependence of the deuterium and oxygen-17 quadrupole coupling constants of methanol was derived. A strong variation of the coupling constants over the measured composition range is evident

Applications of the intermolecular nuclear Overhauser effect. II. The operation of solute-site factors in the interaction of polar solutes with the solvent benzene

1983 ◽  
Vol 36 (11) ◽  
pp. 2227 ◽  
Author(s):  
GR Smith ◽  
B Ternai
Keyword(s):  
Nuclear Overhauser Effect ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Site Factors ◽  
Aromatic Solvent ◽  
Proton Proton ◽  
Solvent Interactions ◽  
Overhauser Effect ◽  
Polar Solutes ◽  
Nuclear Overhauser

By considering the technique involving the measurement of aromatic solvent-induced shifts, and the models which have been proposed from the results of such measurements, it is suggested that the use of the solvent-induced solute proton intermolecular relaxation rate [(1/T1)solvinter] is a better method to study local solvation of solute molecules. Proton relaxation rates obtained for simple solutes in the solvent benzene are analysed in terms of an interaction parameter I, which treats (1/T1)solvinter] in terms of a proton-proton pair distribution function. The resultant dependence between I and a calculated measure of the local polarity of the observed solute is discussed in terms of previously proposed models of solute-solvent interactions.

Molecular Reorientation in Liquid Methanol

1991 ◽  
Vol 46 (1-2) ◽  
pp. 89-94 ◽  
Author(s):  
R. Ludwig ◽  
D. S. Gill ◽  
M. D. Zeidler
Keyword(s):  
Nmr Relaxation ◽  
Quadrupole Coupling Constant ◽  
Dipolar Interaction ◽  
Proton Relaxation ◽  
Coupling Constant ◽  
Relaxation Rates ◽  
Molecular Reorientation ◽  
Quadrupole Coupling ◽  
Relaxation Measurements ◽  
Recent Computer

AbstractOxygen-17 enriched methanol CD317OH was synthesized and 1H as well as 17O nmr relaxation rates were measured in the temperature range 180-310 K. By varying the 17O-content different contributions to the proton relaxation rate could be separated and from the 17O-H dipolar interaction contribution the correlation time of the OH bond was determined. These results are compared to recent computer simulation data. Additional deuteron relaxation measurements on CH3OD yielded the quadrupole coupling constant which increases with falling temperature. The 17O quadrupole coupling constant shows a similar trend with temperature but not as pronounced.

Kernmagnetische Relaxation und Korrelation im System Wasser - Sauerstoff

1965 ◽  
Vol 20 (12) ◽  
pp. 1668-1675 ◽  
Author(s):  
R. Hausser ◽  
F. Noack
Keyword(s):  
Correlation Time ◽  
Pure Water ◽  
Relaxation Times ◽  
Larmor Frequency ◽  
Magnetic Interaction ◽  
Spin Correlation ◽  
Dipolar Interaction ◽  
Proton Spin ◽  
Proton Relaxation ◽  
Effective Distance

The magnetic interaction between the electronic magnetic dipole moment of molecular oxygen dissolved in water and water protons has been investigated by measuring the nuclear magnetic proton relaxation times and their dependence upon oxygen pressure (10–2—200 at), upon the proton LARMOR frequency (0.45 — 160 Mc) and upon temperature (20°C—300°C). The results are interpreted in terms of microscopic correlation times. The dipolar interaction, which is dominant, appears to be modulated in time mainly by the correlation time τS of the 02 electron spin. At 25°C we obtain τS = (1 ± 0.4) · 10-11 sec for the O2 spin correlation time and d= 2.87 ± 0.15 Å for the effective distance of nearest approach between electron and proton spin. The value for the translational correlation time TD > 1.3·10-11 sec at 25°C, somewhat larger than in pure water, might suggest a weak, short-lived bonding between O2 and H2O.

scholarly journals Indirekte Bestimmung kurzer Relaxationszeiten von paramagnetischen Ionen in wäßriger Lösung

1969 ◽  
Vol 24 (3) ◽  
pp. 424-427
Author(s):  
K. Glemser ◽  
U. Haeberlen ◽  
R. Hausser
Keyword(s):  
Relaxation Times ◽  
Dipolar Interaction ◽  
Rare Earth Ions ◽  
Proton Relaxation ◽  
Salt Solutions ◽  
Epr Spectrum ◽  
Relaxation Measurements ◽  
Paramagnetic Salt ◽  
The Difference ◽  
Diamagnetic Salt

AbstractThe width of the first Hfs-line of the Mn++ EPR-spectrum in aqueous solutions with added diamagnetic and paramagnetic iron group or rare earth ions was measured at 3 cm wavelength and at 300 °K. The difference ΔHD in linewidth of Mn++ in the paramagnetic and diamagnetic salt solutions is ascribed to dipolar interaction between Mn++ and the other paramagnetic ions e. g. Co++ , Ni++ and Ce3+ . The relaxation times τs of these ions are too short for the EPR-spectrum to be detected in liquids. From the excess linewidth ΔHD relaxation times Ts for Co++ , Ni++ and Ce3+ are estimated which agree well with τs results from proton relaxation measurements in paramagnetic salt solutions.

Cellular water and proton relaxation times of Thai rice kernels during grain development and storage

2019 ◽  
Vol 88 ◽  
pp. 65-70 ◽  
Author(s):  
Klitsadee Yubonmhat ◽  
Suriya Chinwong ◽  
Nattawoot Maleelai ◽  
Nath Saowadee ◽  
Wiwat Youngdee
Keyword(s):  
Relaxation Times ◽  
Proton Relaxation ◽  
Grain Development ◽  
Cellular Water ◽  
And Storage

Proton relaxation times in7LiCl and6LiCl solutions

1967 ◽  
Vol 13 (4) ◽  
pp. 323-330 ◽  
Author(s):  
Burton P. Fabricand ◽  
Sigmund S. Goldberg
Keyword(s):  
Relaxation Times ◽  
Proton Relaxation

scholarly journals Multiscale Post-Seismic Deformation Based on cGNSS Time Series Following the 2015 Lefkas (W. Greece) Mw6.5 Earthquake

2021 ◽  
Vol 11 (11) ◽  
pp. 4817
Author(s):  
Filippos Vallianatos ◽  
Vassilis Sakkas
Keyword(s):  
Time Series ◽  
Relaxation Time ◽  
Relaxation Times ◽  
Relaxation Mechanism ◽  
Mesoscopic Scale ◽  
Macroscopic Scale ◽  
Epicentral Area ◽  
Arrhenius Dependence ◽  
Seismic Deformation ◽  
Logarithmic Type

In the present work, a multiscale post-seismic relaxation mechanism, based on the existence of a distribution in relaxation time, is presented. Assuming an Arrhenius dependence of the relaxation time with uniform distributed activation energy in a mesoscopic scale, a generic logarithmic-type relaxation in a macroscopic scale results. The model was applied in the case of the strong 2015 Lefkas Mw6.5 (W. Greece) earthquake, where continuous GNSS (cGNSS) time series were recorded in a station located in the near vicinity of the epicentral area. The application of the present approach to the Lefkas event fits the observed displacements implied by a distribution of relaxation times in the range τmin ≈3.5 days to τmax ≈350 days.

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