scholarly journals Theoretical Description of Pulsed RYDMR: Refocusing Zero-Quantum and Single Quantum Coherences

2017 ◽  
Vol 231 (2) ◽  
Author(s):  
Egor A. Nasibulov ◽  
Jan Behrends ◽  
Leonid V. Kulik ◽  
Konstantin L. Ivanov
Keyword(s):  
Magnetic Resonance ◽  
Organic Semiconductors ◽  
Spin Echo ◽  
Pulse Sequences ◽  
Theoretical Description ◽  
Reaction Yield ◽  
Single Quantum ◽  
Paramagnetic Resonance ◽  
Product Operator ◽  
Electron Paramagnetic

AbstractA theoretical description of pulsed reaction yield detected magnetic resonance (RYDMR) is proposed. In RYDMR, magnetic resonance spectra of radical pairs (RPs) are indirectly detected by monitoring their recombination yield. Such a detection method is significantly more sensitive than conventional electron paramagnetic resonance (EPR), but design of appropriate pulse sequences for RYDMR requires additional effort because of a different observable. In this work various schemes for generating spin-echo like signals and detecting them by RYDMR are treated. Specifically, we consider refocusing of zero-quantum coherences (ZQCs) and single-quantum coherences (SQCs) by selective as well as by non-selective pulses and formulate a general analytical approach to pulsed RYDMR, which makes an efficient use of the product operator formalism. We anticipate that these results are of importance for RYDMR studies of elusive paramagnetic particles, notably, in organic semiconductors.

Interaction of Point Defects with Impurities in the Si-SiO2 System and its Influence on the Properties of the Interface

2009 ◽  
Vol 156-158 ◽  
pp. 145-148 ◽  
Author(s):  
Daniel Kropman ◽  
E. Mellikov ◽  
K. Lott ◽  
Tiit Kärner ◽  
Ivo Heinmaa ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Magnetic Resonance ◽  
Fermi Level ◽  
Point Defects ◽  
Interface Properties ◽  
Hydrogen Ions ◽  
Paramagnetic Resonance ◽  
Proposed Model ◽  
P Type ◽  
Electron Paramagnetic

The results of investigation of the point defect generation and interaction with impurities in the Si-SiO2 system during the process of its formation by means of electron paramagnetic resonance (EPR) and nucleous magnetic resonance (NMR) technique are presented. It has been shown that the diference in point defects interaction with hydrogen at the Si-SO2 interface with n- and p-type conductivity are connected with the sign of hydrogen ions incorporation dependence on the Fermi level position in accordance with the proposed model. The interface properties may be improved by laser irradiation.

Magnetic Resonance Imaging: Comparative Study of Radiofrequency Pulse Techniques in the Evaluation of Focal Cerebral Ischemia

Neurosurgery ◽  
1985 ◽  
Vol 16 (4) ◽  
pp. 502-510 ◽  
Author(s):  
Joseph M. Zabramski ◽  
Robert F. Spetzler ◽  
Benjamin Kaufman
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Focal Cerebral Ischemia ◽  
Spin Echo ◽  
Pulse Sequences ◽  
Artery Occlusion ◽  
Primate Model ◽  
Cross Sectional ◽  
Tissue Contrast ◽  
Rf Pulse

Abstract The recently developed technique of magnetic resonance (MR) imaging utilizes radiofrequency (RF) radiation in the presence of a strong magnetic field to provide cross sectional displays of body anatomy similar to computed tomography, When utilizing MR, the operator alters tissue contrast electronically by changing RF pulse sequences. The three most frequently used RF pulse sequences are partial-saturation (PS), inversion-recovery (IR), and spin-echo (SE). We evaluated the sensitivity of these RF sequences to detect ischemic changes in our primate model. Serial MR scans were carried out using all three pulse formats 5 to 60 hours after middle cerebral artery occlusion (MCAO) in four animals. SE- and IR-sequenced proton MR images readily identified areas of evolving infarct 5 to 6 hours after MCAO, whereas PS scans that were performed during this acute period appeared normal. From 24 to 60 hours after MCAO, PS-sequenced scans showed focal areas of progressively decreasing signal intensity. However, SE and IR scans performed at the same intervals always demonstrated more extensive tissue changes. The basis of MR imaging, the effects of altering RF pulse sequences, and the resulting interpretation of changes observed in MR sections are presented. (Neurosurgery 16: 502-510, 1985)

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