Isotopologue

An isotopologue is a version of a molecule that contains specific isotopes of the elements in it.

Examples

Heavy water is an isotopologue of water. They have the same chemical formula, H₂O, but with different isotopes of hydrogen. Heavy water contains deuterium, with one proton and one neutron, which is heavier than the normal hydrogen-1 isotope in "light" water, which only has a proton.

Heavy water is an example of a deuterated solvent. A deuterated solvent is an isotopologue of some solvent, like ethanol or hexane, where every hydrogen atom is the deuterium isotope. Deuterated solvents are used in nuclear magnetic resonance spectroscopy.