3. Applications or implementation

Thermodynamics shows that the equilibrium point of a chemical bond decreases when heavy isotopic substitutions are made within the same molecule. The number of doubly-substituted isotopologues characterized by lower vibrational energy levels increases with decreasing temperature. . The abundance of doubly-substituted isotopologues can thus be used as a thermometer when the system is (or is assumed to be) at equilibrium. This measurement is thus relevant for...