Chemical shift
(δ): The position of a signal
along the x-axis of an NMR
spectrum. More precisely, the difference between the
frequency of photon
required for nuclear
spin
flip of the nucleus in question and nuclear
spin
flip of a reference molecule
-- sometimes tetramethylsilane
(TMS)
or CDCl3
-- divided by the operating frequency of the NMR
spectrometer. (Equation given below.) Not to be confused
with δ+
or δ-,
symbols used to indicate partial charge.
