Nucleus, resonance

In a continuous-wave NMR (CW NMR) experiment the HY frequency is slowly scanned and each nucleus resonates at its specific frequency, which is a function of the examined nucleus and the electron density that surrounds it. This experiment can be long and tedious because if high resolution is desired, the frequencies must be swept very slowly. If the concentration of the examined nucleus is low, a large number of repeated sweeps may be needed to obtain a detectable signal. 

The solid state high resolution n.m.r. spectra were run on a CXP 200 BruKer spectrometer in which the 31P nucleus resonates at 81 MHz. Samples used were finely powedered and hand-tamped in glass tubes. The spectra were recorded using the Proton Enhanced Nuclear Induction Technique (6) on the same basis of a one shot cross polarization and high power decoupling during acquisition. A capillary tube of trimethylphosphate inserted in the powder sample is used as internal reference. 

Stuart models show that nucleus resonance stabilization of the enol double bond is possible only for the thiophene ester. It is possible that resonance stabilization of the radical resulting from the enolic double bond (with the peroxide or ketohydroperoxide forms as intermediates)... 

For low naturally abundant nuclei, such as the nucleus, resonance lines reflecting the chemical shift anisotropy (CSA) can be observed for solid organic materials by eliminating the effects of local field with use of the so-called dipolar decoupling method. However, the CSA resonance lines are usually broad and, therefore, the respective CSA lines are superposed with each other for polymers composed of different C species. To separately measure these CSA lines, the following different methods were proposed ... 

The carbon-13 nucleus resonates at 15 09 Mc./sec. in a magnetic field of 14,092 gauss. Since this isotope has a low magnetic moment and is present in only 1% of natural carbon, the sensitivity of the resonance signal in natural abundance samples is only about 1/6500 of that of an equal number of proton nuclei. The spin lattice relaxation time (Tj) of the nucleus varies from a few seconds to several... 

In general, the carbonyl carbon nucleus resonates at low field, in regions free from interference from other absorptions and is uncoupled. Measurement of the carbonyl group chemical shifts has been a particularly fruitful method for gaining information about the electronic structural features of this polar grouping. 

Acids in which the aromatic nucleus resonates with neither the acidic resonator nor the acidic group. Examples are C6H5CH2-... 

Nuclear magnetic resonance Electron spin resonance NMR ESR Bulk samples environment of atom (e.g., Fe) Chemical state and free High y-rays by nucleus Resonance in magnetic elements No surface info —... 

The key to any medical imaging technique is to know which part of the body gives rise to which signal. In MRI, spatial information is encoded using magnetic field gradients. Recall that a linear relationship exists between the frequency at which a nucleus resonates... 

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