Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 4

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  76.70.Fz
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Intermolecular Magnetic Spin-Spin Interaction in Asphaltene Suspensions at 1.53 mT

100%
Ovalioglu H., Kirimli H., Akay C.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
806-809
EN
In this study, Overhauser effect (OE) type of dynamic nuclear polarization (DNP) experiments were performed to study suspensions of MC800 asphaltene in bromopentafluorobenzene, chloropentafluorobenzene and hexafluorobenzene aromatic solvents. The experiments were performed at a low field of 1.53 mT in a double-resonance nuclear magnetic resonance (NMR) spectrometer. In this technique the nuclei of diffusing solvent molecules and the unpaired electron existing on the asphaltene micelles interact magnetically. The DNP parameters were determined. Additionally, the interactions between ¹⁹F nuclei of the solvent and the electrons delocalized on the asphaltene are interpreted. The highest enhancement factor value (5.90) was obtained for the hexafluorobenzene solvent medium, because between these, hexafluorobenzene has the highest fluorine atom number. The solvent molecules attach to the colloidal asphaltene particles for a very short time forming complexes and making scalar interaction. Morphologies of asphaltene surfaces depending on the solvent effects were observed by using scanning electron microscopy (SEM).
2
Content available remote

Intermolecular Effects of Fluorocarbons on MC800 Asphaltene and their Characterization

100%
Kirimli H., Ovalioglu H., Akay C.
Acta Physica Polonica A
|
2017
|
vol. 131
|
issue 3
336-338
EN
Nuclear magnetic resonance and dynamic nuclear polarization experiments were performed to study suspensions of asphaltene in the fluorocarbons at a low magnetic field of 1.53 mT, at room temperature. The asphaltene was extracted from MC800 liquid asphalt, which was of Heavy Iran origin. The elemental composition and the surface morphology of the asphaltene were determined by scanning electron microscopy and energy dispersive X-ray analysis. Intermolecular spin-spin interactions occur between nuclear spins of hydrogen in the solvent medium and the free electron spins in the asphaltene micelles. The electron paramagnetic resonance spectrum of the asphaltene was obtained and the saturation experiments were applied to the samples prepared in vacuum. The main ¹H DNP parameters were listed. Chemical composition and molecular structure of the asphaltene were analyzed. Scanning electron microscope images have shown that asphaltenes are constituted of agglomerated particles and smooth surfaces. Energy dispersive X-ray analysis has shown that the most abundant element is carbon.
3
Content available remote

Spatial Localized Double-Quantum NMR Heteronuclear Coherence Transfer in Solids by Indirect Detection

100%
Demco D., Ardelean I.
Acta Physica Polonica A
|
1996
|
vol. 89
|
issue 5-6
699-714
EN
The spatial localization of the double-quantum NMR heteronuclear coherence transfer in solids, in the presence of a main magnetic field gradient is analyzed. The indirect detection procedure by which the dipolar order of the abundant spin system with I=1/2 is transferred to the double-quantum coherence of the quadrupole nucleus with S=1 and back to the I-spin dipolar order is considered. The slice profile and the cross-relaxation rates are evaluated as a function of the experimental parameters and the sample relevant NMR quantities. The possibility to use this slice selective procedure for imaging and volume localized spectroscopy of quadrupole nuclei in high magnetic fields is discussed.
4
Content available remote

Spatial Localized Single Quantum Heteronuclear Polarization Transfer

100%
Demco D. E., Ardelean I.
Acta Physica Polonica A
|
1994
|
vol. 86
|
issue 3
407-425
EN
The existence of a strong spatial localization for the efficiency of cross-polarization by single quantum transition in the presence of a main field gradient was evidenced . The case of the solids with strong dipolar interactions has been analyzed. The slice profile of the transferred polarization was evaluated for different cross-polarization procedures. The spatial localization is superior as compared with the spin-locking slice selection method.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.