Effects of 5f-elements on electronic structures and spectroscopic properties of gold superatom model

5f-elements encaged in a gold superatomic cluster are capable of giving rise to unique optical properties due to their hyperactive valence electrons and great radial components of 5f/6d orbitals. Herein, we review our first-principles studies on electronic structures and spectroscopic properties of a series of actinide-embedded gold superatomic clusters with different dimensions. The three-dimensional (3D) and two-dimensional (2D) superatom clusters possess the 18-electron configuration of 1S²1P⁶1D¹⁰ and 10-electron configuration of 1S²1P⁴1D⁴, respectively. Importantly, their electronic absorption spectra can also be effectively explained by the superatom orbitals. Specifically, the charge transfer (CT) transitions involved in surface-enhance Raman spectroscopy (SERS) spectra for 3D and 2D structures are both from the filled 1D orbitals, providing the enhancement factors of the order of ~10⁴ at 488 nm and ~10⁵ at 456 nm, respectively. This work implies that the superatomic orbital transitions involved in 5f-elements can not only lead to a remarkable spectroscopic performance, but also a new direction for optical design in the future.