The difference between the resonance frequencies of a given nucleus and a standard reference nucleus. It arises due to interactions of electrons with the applied magnetic field that generate local magnetic fields around atomic nuclei.
(delta - see Greek symbols) - the change in the Larmor frequency of a given nucleus when bound in different sites in a molecule, due to the magnetic shielding effects of the orbiting electrons. Chemical shifts make possible the differentiation of different molecular compounds and different sites within the molecules in high resolution NMR spectra. The amount of the shift is proportional to magnetic field strength and is usually specified in parts per million (ppm) of the resonance frequency relative to a standard.
a variation in the nominal Larmor frequency for a particular isotope within the imaging volume. The amount of shift introduced is directly proportional to the strength of the magnetic field, and is specified in parts per million (ppm) of the resonant frequency.
An atomic property that varies depending on the chemical and magnetic properties of an atom and its arrangement within a molecule. Chemical shifts are measured by NMR spectroscopists to identify the types of atoms in their samples.
A variation in the resonance frequency of a nuclear spin due to the chemical environment around the nucleus. Chemical shift is reported in ppm. [ Chapter 4
In nuclear magnetic resonance (NMR), the chemical shift describes the dependence of nuclear magnetic energy levels on the electronic environment in a molecule. Chemical shifts are relevant in NMR spectroscopy techniques such proton NMR and carbon-13 NMR.