NMR Chemical Shift on the δ Scale

NMR chemical shift is the value used to show where a sample signal appears in a spectrum. It is measured by comparing the sample peak with tetramethylsilane, or TMS, which is added as an internal reference.

The difference between the sample and TMS absorption frequencies, measured in Hz, is divid...

The position of the NMR absorption frequency is expressed in terms of how far it is shifted from the signal of a reference compound, usually TMS.

The frequency difference is divided by the instrument operating frequency to yield the chemical shift, a dimensionless quantity.

Expressed in parts per million or ppm, chemical shifts are...