Light Emission from Transuranic Elements

Luminescence of the transuranic actinides continues to gain interest given the series' unequivocal importance in the development of nuclear energy, technology, and radiotherapies. Luminescence acts as a key identifier for transuranic radioisotopes, with spectra displaying characteristic peaks for each actinide. This review aims to be a comprehensive source for years of studies into the luminescence of Np, Pu, Am, Cm, Bk, Cf, and Es, including insights into their electronic structures and coordination chemistry. This review highlights the photophysical properties of transuranic actinides in a range of chemical environments, including aquo ions, single crystals, metal-ligand complexes, and cases of coordination with proteins. Unique luminescence mechanisms are discussed, including antenna effect, ligand-to-metal charge transfer, two-photon excitation, circularly polarized luminescence, and self-induced luminescence from radioactive decay. The emission spectra for a multitude of species across the series have been extracted and overlaid on singular plots to highlight similarities and oddities within each element. Observations of actinide luminescence have further solidified chemists' understanding of the electronic structure of 5f elements. This review emphasizes how luminescence has helped assign 5f transition states. Such fundamentals contribute to growing interest in f-block chemistry and enable safer use of the actinides in human endeavors.