Solid State NMR Evaluation of Natural Resin/Clay Nanocomposites

2009 ◽  
Vol 4 ◽  
pp. 117-126 ◽  
Author(s):  
Emerson O. da Silva ◽  
Maria I.B. Tavares ◽  
José S. Nogueira
Keyword(s):  
Relaxation Time ◽  
Solid State ◽  
Polymer Matrix ◽  
Spin Diffusion ◽  
Environmental Changes ◽  
Relaxation Times ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Spin Lattice ◽  
Natural Resin

NMR nuclear relaxation times have been used by Tavares et al as a methodology to characterize the nano materials, especially nanocomposites, because NMR offers a great variety of relaxation parameters. The spin-lattice relaxation time, with a time constant T1, have been explored to get as much information as possible from the measurements of the spin-lattice proton relaxation (T1H), which can measure the fraction of available polymer/clay interface as well as the dispersion homogeneity of those interfaces actually formed. The spin-lattice has been evaluated since this relaxation time confirms the T1 and can give additional information to nanocomposite clay dispersion. The NMR relaxation times are sensitive to the chemical environmental, changes in the polymer matrix; chemical structure and interaction process, because they depend on the domain distribution and sample homogeneity, since they are measured in the solid state via intermolecular chains interaction and/or spin diffusion. The T1 relaxation time of the nanocomposite decreased very much in relation to the natural resin, according to the increase in the exfoliation clay process, forming a nanocomposite with polymer matrix around the clay lamella.

scholarly journals Observation of an environmentally insensitive solid-state spin defect in diamond

Science ◽  
2018 ◽  
Vol 361 (6397) ◽  
pp. 60-63 ◽  
Author(s):  
Brendon C. Rose ◽  
Ding Huang ◽  
Zi-Huai Zhang ◽  
Paul Stevenson ◽  
Alexei M. Tyryshkin ◽  
...  
Keyword(s):  
Solid State ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Zero Phonon Line ◽  
Spin Lattice ◽  
Network Applications ◽  
Field Noise ◽  
Quantum Science ◽  
State Spin

Engineering coherent systems is a central goal of quantum science. Color centers in diamond are a promising approach, with the potential to combine the coherence of atoms with the scalability of a solid-state platform. We report a color center that shows insensitivity to environmental decoherence caused by phonons and electric field noise: the neutral charge state of silicon vacancy (SiV0). Through careful materials engineering, we achieved >80% conversion of implanted silicon to SiV0. SiV0 exhibits spin-lattice relaxation times approaching 1 minute and coherence times approaching 1 second. Its optical properties are very favorable, with ~90% of its emission into the zero-phonon line and near–transform-limited optical linewidths. These combined properties make SiV0 a promising defect for quantum network applications.

Method Dependence of Proton Spin-Lattice Relaxation Analysis in Biologic Tissues

1989 ◽  
Vol 30 (1) ◽  
pp. 97-100 ◽  
Author(s):  
M. Komu ◽  
A. Alanen ◽  
H. Määttänen ◽  
M. Kormano
Keyword(s):  
Relaxation Time ◽  
Spin Echo ◽  
Weighted Average ◽  
Proton Spin ◽  
Point Method ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Spin Lattice ◽  
Exponential Relaxation ◽  
Data Point

Spin-lattice proton relaxation times (T1) in several biologic and phantom samples have been measured and analysed by using standard inversion recovery (IR) and spin echo (SE) sequences at 0.02 T. The average T1 of the sample was measured with the two-data point method. In the case of bi-exponential relaxation the value of a single T1 is strongly dependent on the T1 and TR selected. With short TI the T1 value obtained by using the two point method is approximately equal to the weighted average of the two relaxation time components (T1s and T1l), while at long inversion times TI the single T1 is more dependent on the long component T1l. The more the true short and long relaxation time components T1s and T1l of the bi-exponential relaxation differ from each other, the greater is the potential error, provided that the weights ws and wl do not differ very much. When two-data point analyzing method is used, the possible multi-exponential behaviour of the relaxation in tissues will be missed. For more reliable T1 values a series of images with as many values of TI as possible should be taken. Knowledge of true multi-exponential relaxation parameters helps in optimizing the sequence parameters and the image contrast between the various tissues.

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.

A proton relaxation study of the conformations of some purine mononucleotides in aqueous solution

1982 ◽  
Vol 60 (23) ◽  
pp. 2976-2983 ◽  
Author(s):  
C. F. G. C. Geraldes ◽  
H. Santos ◽  
A. V. Xavier
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Spin Lattice ◽  
Population Distributions ◽  
Anti Conformation ◽  
Relaxation Study ◽  
Interproton Distances

A method is described by which conformationally averaged interproton distances in mononucleotides are obtained from measured proton spin-lattice relaxation times and published crystal coordinates of selected mononucleotides. The glycosil conformations of adenosine in D2O and DMSO-d6 and of 5′-AMP, 5′-GMP, 3′-AMP, and 2′-AMP in D2O are examined by quantitative analysis of the conformationally averaged interproton distances in terms of population distributions obtained from potential energy calculations. 5′-AMP strongly prefers a single glycosyl conformation in the anti range. Besides the anti conformation, 5′-GMP has a secondary minimum in the syn region. 3′-AMP, 2′-AMP, and adenosine have more latitude in their glycosyl torsion angle values, with both the syn and anti regions highly populated.

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