Actinide-embedded gold superatom models: Electronic structure, spectroscopic properties, and applications in surface-enhanced Raman scattering

Actinide elements encaged in a superatomic cluster can exhibit unique properties due to their hyperactive valence electrons. Herein, the electronic and spectroscopic properties of Th@Au₁₄ are predicted and compared with that of the isoelectronic entities [Ac@Au₁₄]^- and [Pa@Au₁₄]⁺ using density functional theory. The calculation results indicate that these clusters all adopt a closedshell superatomic 18-electron configuration of the 1S²1P⁶1D¹⁰ Jellium state. The absorption spectrum of Th@Au₁₄ can be interpreted by the Jelliumatic orbital model. In addition, calculated spectra of pyridine-Th@Au₁₄ complexes in the blue laser band exhibit strong peaks attributable to charge transfer (CT) from the metal to the pyridine molecule. These charge-transfer bands lead to a resonant surface-enhanced Raman scattering (SERS) enhancement of ~10⁴. This work suggests a basis for designing and synthesizing SERS substrate materials based on actinide-embedded gold superatom models.