Offset frequency

The offset frequency determines the center point of the spectrum. The chemical-shift (d) range observed in the final spectrum extends from -1/2SW to +1/2SW (where SW is the spectral window) about the offset (in ppm). Thus, an offset of 5 ppm with a spectral window of 10 ppm yields a spectrum which starts at 0 ppm and ends at 10 ppm.