Passage: Deuterium oxide is used in nuclear magnetic resonance spectroscopy when using water as solvent if the nuclide of interest is hydrogen. This is because the signal from light-water (1H2O) solvent molecules interfere with observing the signal from the molecule of interest dissolved in it. Deuterium has a different magnetic moment and therefore does not contribute to the 1H-NMR signal at the hydrogen-1 resonance frequency.

Question: What has a magnetic moment that is different?
Deuterium