High stability of the He atom confined in a U@C60 fullerene

Abstract

To understand the confined nature of rare gases in endohedral metallofullerenes (EMFs) encapsulating actinide metals, here we study the interaction between a He atom and uranium metallofullerene U@C₆₀ in a UHe@C₆₀ system, using density functional theory (DFT). Analysis of the electron density indicates no observable electron clouds overlap between the He atom and U atom/fullerene cage. Direct contributions from the atomic orbitals to molecular orbitals (MOs), show that the 1s shell electrons of the He atom account for >1% contribution to only three MOs, and they are all far beneath the frontier molecular orbitals. Furthermore, the modulations of the He atom on the UV-Vis, infrared and Raman spectra are almost negligible. Our work highlights the high stability of the He atom in the actinide metallofullerenes, and it can also help to understand the interaction between fission products of actinide elements and the synthesizing process of EMFs.