chemical shift


Also found in: Encyclopedia, Wikipedia.

chem·i·cal shift

dependence of the resonance frequency of a nucleus on the chemical binding of the atom or molecule in which it is contained. See: chemical shift artifact.

chemical shift

(in nuclear magnetic resonance spectrometry) the position of a resonance in the substance of interest relative to the position of the resonance of a standard. Nonequivalent atoms of a molecule have different chemical shifts.

chemical shift

An MRI term for a variation in the nominal Larmor frequency for a particular isotope within the imaging volume. The amount of chemical shift is directly proportional to the strength of the magnetic field, and is specified in parts per million of the resonant frequency.
References in periodicals archive ?
Table-2: 1H-NMR chemical shifts (400 MHz, CDCl3) of compound 2.
For elucidation of the origin of the chemical shift perturbations of aromatic proton signals, detailed information from all over the T[F.
19) In clinical practice, however, most radiologists evaluate chemical shift change visually or qualitatively using muscle or spleen as the internal reference organ.
Na+, would cause change in the chemical shift of phosphorus, shifting it to the more positive value.
The intensity of the chemical shift at 110 to 115 ppm was higher than that at 105 ppm, indicating the tannins in the bark alkaline extractives obtained from the mountain pine beetle-infested lodgepole pine through autoclave extraction were mainly procyanidin type.
Assigning stereodiversity of the 27-Me group of furostane-type steroidal saponins via NMR chemical shifts.
In the molybdenum complex the most deshielded 13C NMR signal corresponds to the carbonyl group (C=O) by showing the highest chemical shift value (d 177) due to lower excitation energy of n-p as well as the intramolecular hydrogen bonding with proton of C5-OH group.
Carbon has a large chemical shift range of approximately 250 ppm and using composite pulse decoupling there is usually a single peak per carbon atom in the molecule making carbon spectra much more informative than proton spectra.
The chemical shift tells which types of atoms are there, while the intensity speaks to how many there are.
Chemical shift imaging is the principal technique employed in the MR evaluation of adrenal lesions using in-and out-of-phase techniques, and exploits the presence of abundant intracellular lipid in adenomas that helps to distinguish them from non-adenomatous lesions.
2008) compiled a heteronuclear single quantum coherence-based metabolite chemical shift database that contains only NMR spectra of standard compounds measured under standardized conditions.