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Chapter 7

Principles of Nuclear Magnetic Resonance

Risonanza Magnetica Nucleare (NMR): Panoramica
Risonanza Magnetica Nucleare (NMR): Panoramica
Nuclear magnetic resonance (NMR) is a phenomenon exhibited by certain nuclei that can absorb characteristic radio frequency radiation under certain ...
Nuclei atomici: spin nucleare
Nuclei atomici: spin nucleare
All atomic particles possess an intrinsic angular momentum, or 'spin'. Electrons, protons, and neutrons each have a spin value of ½, although ...
Nuclei atomici: momento magnetico nucleare
Nuclei atomici: momento magnetico nucleare
All atomic nuclei are positively charged. When they have a nonzero spin, they behave like rotating charges. As a consequence of their charge and spin, ...
Nuclei atomici: panoramica dello stato di spin nucleare
Nuclei atomici: panoramica dello stato di spin nucleare
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the ...
Nuclei atomici: distribuzione della popolazione dello stato di spin nucleare
Nuclei atomici: distribuzione della popolazione dello stato di spin nucleare
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy ...
Nuclei atomici: Frequenza di precessione di Larmor
Nuclei atomici: Frequenza di precessione di Larmor
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) ...
Nuclei atomici: Risonanza magnetica
Nuclei atomici: Risonanza magnetica
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external ...
Nuclei atomici: processi di rilassamento nucleare
Nuclei atomici: processi di rilassamento nucleare
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin ...
Nuclei atomici: tipi di rilassamento nucleare
Nuclei atomici: tipi di rilassamento nucleare
Relaxation in NMR systems is a first-order exponential decay and can occur by either spin–lattice or spin–spin mechanisms. Spin–lattice ...
Spettrometri NMR: Panoramica
Spettrometri NMR: Panoramica
NMR spectrometers consist of a strong magnet, a radiofrequency transmitter, and a detector attached to a computer console for recording spectra of samples ...
Spettrometri NMR: impulsi a radiofrequenza e sequenze di impulsi
Spettrometri NMR: impulsi a radiofrequenza e sequenze di impulsi
A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a ...
Spettrometri NMR: risoluzione e correzione degli errori
Spettrometri NMR: risoluzione e correzione degli errori
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction ...
Schermatura diamagnetica dei nuclei: corrente diamagnetica locale
Schermatura diamagnetica dei nuclei: corrente diamagnetica locale
An applied magnetic field causes the electrons present in the molecule to circulate, setting up a local diamagnetic current within the molecule. The local ...
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