Isotopic Labeling in IR Spectroscopy of Surface Species: A Powerful Approach to Advanced Surface Investigations

This paper summarizes the main applications of isotopic substitution in infrared surface studies, including surface characterization, determination of the structure of adsorbed species, and clarification of catalytic reaction mechanisms. While acknowledging the key pioneering contributions to the field, we focus on the recent developments and the future potential of the technique. The applications are grouped into two main categories, according to the extent of isotopic substitution. The first category involves systems in which one or more atoms in specific positions are fully replaced by their isotopes. This classical approach remains fundamental for establishing whether the spectral signature of a given compound is related to the presence of a specific atom. The second category concerns partial isotopic exchange. These studies unravel different vibrational interactions and provide valuable structural information that cannot be obtained through full substitution. Finally, we discuss some applications related to the mechanisms of catalytic reactions. The perspective concludes with a discussion of the emerging opportunities and future perspectives for more systematic and effective implementation of isotopic substitution in infrared surface studies.