Inhomogeneous Dipolar Broadening and Hyperfine Shifts of Protons Resonance Lines in Solution with Paramagnetic Impurities

1990 ◽  
pp. 215-216 ◽  
Author(s):  
E. Belorizky ◽  
P. Fries ◽  
W. Gorecki ◽  
M. Jeannin ◽  
P. Maldivi ◽  
...  
Keyword(s):  
Paramagnetic Impurities

scholarly journals Single-Sided Portable NMR Investigation to Assess and Monitor Cleaning Action of PVA-Borax Hydrogel in Travertine and Lecce Stone

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3697
Author(s):  
Valeria Stagno ◽  
Chiara Genova ◽  
Nicole Zoratto ◽  
Gabriele Favero ◽  
Silvia Capuani
Keyword(s):  
Pore Size ◽  
Experimental Conditions ◽  
Non Invasive ◽  
Bedding Planes ◽  
Paramagnetic Impurities ◽  
Two Samples ◽  
Action Time ◽  
Paramagnetic Agents ◽  
Portable Nmr ◽  
Non Destructive

In this work, we investigated the potential of PVA-borax hydrogel for cleaning limestones and the dependence of the cleaning on the porosity of the rock and on the action time of the hydrogel treatment. Towards this goal, we used a nuclear magnetic resonance (NMR) spectrometer, developed for non-invasive and non-destructive applications on cultural heritage. T2-NMR parameters were quantified on different samples of Lecce stone and Travertine cut perpendicular (Pe) and parallel (Pa) to the bedding planes under different experimental conditions: untreated samples, treated with Paraloid B72 and cleaned with PVA-PEO-borax hydrogel applied for 4 min and 2 h. The T2 results suggest that the effectiveness of the cleaning strongly depended on the porosity of the stones. In Lecce stone, the hydrogel seemed to eliminate both the paramagnetic impurities (in equal measure with 4 min and 2 h treatment) and Paraloid B72. In Travertine Pe, characterized by a smaller pore size compared to Lecce stone, no significant effects were found regarding both the cleaning and the treatment with Paraloid B72. In Travertine Pa, characterized by a larger pore size than the other two samples, the hydrogel seemed to clean the paramagnetic agents (it worked better if applied for a longer time) but it did not appear to have any effect on Paraloid B72 removal.

Optimization of Sample Holder Materials for Sensitive Magnetometry Measurements at Low Temperatures

2004 ◽  
Vol 825 ◽  
Author(s):  
I. Bossi ◽  
N.R. Dilley ◽  
J. R. O'Brien ◽  
S. Spagna
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Magnetic Response ◽  
Sample Holder ◽  
Magnetization Measurements ◽  
Temperature Range ◽  
Paramagnetic Impurities ◽  
Fused Quartz

AbstractMagnetization measurements were performed as a function of magnetic field H and temperature T on samples of nine different materials including clear fused quartz, cartridge brass, G-10 glass-reinforced epoxy, acetal homopolymer, glass-filled acetal, phenolic, and other plastics. A small yet distinct amount of ferromagnetic or paramagnetic impurities is observed in all the materials investigated in this study except quartz. In contrast, the magnetic response of quartz is typical of a diamagnet over the temperature range 5 K to 300 K. The volume susceptibility is equal to −4.4×10−7 (cgs) over the whole temperature range.

Energy Gap in Superconductors Containing Paramagnetic Impurities

1962 ◽  
Vol 9 (7) ◽  
pp. 315-316 ◽  
Author(s):  
F. Reif ◽  
Michael A. Woolf
Keyword(s):  
Energy Gap ◽  
Paramagnetic Impurities

Magnetocaloric Properties of AlFe2B2 Including Paramagnetic Impurities of Al13Fe4

2018 ◽  
Vol 73 (10) ◽  
pp. 1555-1560 ◽  
Author(s):  
J. W. Lee ◽  
M. S. Song ◽  
K. K. Cho ◽  
B. K. Cho ◽  
Chunghee Nam
Keyword(s):  
Paramagnetic Impurities ◽  
Magnetocaloric Properties

Electron spin resonance of paramagnetic impurities in antiferromagnetic compounds

1991 ◽  
Vol 433 (1888) ◽  
pp. 461-468 ◽  
Keyword(s):  
Internal Field ◽  
Host Lattice ◽  
Nuclear Resonance ◽  
Dipolar Field ◽  
Exchange Field ◽  
Paramagnetic Impurities ◽  
Resonance Frequencies ◽  
Spin Resonance ◽  
Impurity Ions ◽  
Impurity Ion

The possibility of magnetic resonance measurements on an impurity in an antiferromagnetic host lattice is discussed. The ion is subject to an internal field B int ; consisting of B dip , the dipolar field generated by the antiferromagnetic moments of the host ions, that can be calculated, and an exchange field B E . For a simple two sublattice antiferromagnet, two resonance frequencies should be observed; equations for their angular dependence are given, including the effect of hyperfine interaction. Impurity ions with Kramers doublets are discussed, together with ions with singlet ground states, for which enhanced nuclear resonance should be possible. A number of simple antiferromagnetic compounds of lanthanide (4f) ions that order at liquid helium temperatures are mentioned briefly, but for simplicity, the discussion is concentrated on GdVO 4 as the host lattice. A formula, based on the known exchange field in the host lattice, is deduced for its effect on the impurity ion.

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).

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