Use of nuclear magnetic resonance in chemistry

In order to realize the resonance absorption of an alternating magnetic field, one should have a sample with nuclei that possess nonzero magnetic moments, i.e., nonzero spin quantum number. The nuclei (protons), and some others have such nonzero 

The purpose of the constant magnetic field is to split the single level in two due to the nuclear Zeeman effect. The alternative electromagnetic field 5(co) facilitates transitions between sublevels. The third coil is to measure absorption. The principle difference between NMR and FRS is as follows on account of its enormous resolution, y resonance allows one to define the superfine structure investigating the transition between different nuclei states (levels) with different /, whereas NMR allows one to measure the transition 

Consider the PMR ability using the example of the ethyl alcohol molecule CH3-CH2-OH. It contains six protons in three different atomic groups. However, only hydrogen protons give a contribution to the spectrum in the given frequency range. 

The PMR spectrum of ethyl alcohol obtained by a spectrometer with a very low resolution would contain only one spectral line to which all the protons contribute simultaneously. The information that can be obtained from such a spectrum is restricted by the statement that in fact there are hydrogen atoms in the sample. Substitution of hydrogen by, say, fluorine atoms would remove the signal completely. 

How small the differences in the electron shell of hydrogen atoms in different positions, this difference is exhibited in the diamagnetic screening of the given nucleus. This signifies that not only will the external magnetic field with the induction Bq ad on the given proton, but an additional local field as weU, specific only to this particular atom. 

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