Principle : The NMR technique is non-destructive, extremely rich and powerful, which allows to probe matter at the nanoscale and to extract structural information is very local on the materials studied.
some nuclei, like the nucleus of 1h hydrogen atom (a proton), are sensitive to the presence of a magnetic field. these nuclei have a magnetic behavior similar to that of the needles snapped. we will use this analogy to familiarize ourselves with the phenomenon of nuclear magnetic resonance. in the absence of any magnetic field, a magnetic needle orients itself in any manner. in the presence of a magnetic field, it orients in the same direction and the same direction as this magnetic field. to change this orientation, it is necessary to provide energy to the magnetic needle, for example in the form of mechanical energy by moving the needle manually. the phenomenon is similar with the nuclei 1h of a molecule : their magnetic property (called spin), similar to that of a magnetic needle is oriented in the same direction as the magnetic field of the spectrometer. to change this orientation, it is necessary to make to the kernel 1 hour a quantum of energy by an electromagnetic wave of particular frequency, called the resonant frequency. this phenomenon is called nuclear magnetic resonance (nmr). the resonance frequency of a proton depends on its electromagnetic environment, that is to say, the presence of various other magnetic fields in its surroundings, created by the neighbouring atoms according to their electronegativity. nmr spectroscopy uses the phenomenon of resonance. in an nmr spectrometer, the sample containing the species studied is subjected to an intense magnetic field and is traversed by the electromagnetic waves. the device measures the resonant frequencies of the different nuclei contained in the species studied. it converts it into a quantity called the chemical shift, which does not depend on the magnetic field of the measuring device, in contrast to the resonance frequency. more the magnetic field of the spectrometer used is intense, the more the spectrum obtained is accurate. nmr spectroscopy can be applied to other nuclei, for example, carbon-13c, fluorine 19f, the phosphorus 31p,..