Superatomic Orbital Splitting in Coinage Metal Nanoclusters

Abstract

The superatomic orbital splitting (SOS) method is developed to understand the electronic structures of coinage metal nanoclusters, in which delocalized electron counts are not magic numbers. Because the symmetry of a metal core can significantly affect the electronic structure of a nanocluster, this method takes the shape of the core into account in determining the order of group orbital levels. By taking nanoclusters as superatoms, a highly positively charged core is established by removing the ligands and staples. The superatomic orbitals split into group orbitals at different energy levels because of the nonspherical shape of the cluster core. Therefore, the electron configuration of the nonmagic-number nanocluster can be qualitatively analyzed without quantum chemical calculations, which is very important for understanding the stability of the cluster.

An Overview on Coinage Metal Nanocluster-Based Luminescent Biosensors via Etching Chemistry

“…The size of metal NCs is generally less than 3 nm, which is close to the electron Fermi wavelength [ 1 , 2 , 3 ]. Metal NCs therefore exhibit some unique physicochemical properties different from other nanomaterials, such as luminescence, chirality, magnetic, and catalytic properties [ 4 , 5 , 6 , 7 ]. Among them, the luminescence of metal NCs is not only adjustable, but also has the characteristics of large Stokes shift, long luminescence lifetime, and good stability [ 8 , 9 ].…”

Splitting of Degenerate Superatomic Molecular Orbitals Determined by Point Group Symmetry

“…Notably, the irreducible representations attributed to these orbitals are derived from structural property anal-ysis by first-principles calculations and are confirmed to be consistent with the 𝐷 5𝑑 symmetry in group symmetry theory. [16,35] This finding implies that the reduction in the C 2− 20 symmetry from 𝐼 ℎ to 𝐷 5𝑑 leads to the splitting of molecular orbitals with the same angular momentum. Figure 2(a) clearly shows that the energy differences of these split SAMOs originating from the same angular momentum gradually increase as expansion and compression proceed.…”

“…[20,21] Additionally, although the metal cores in some ligandprotected coinage metal clusters cannot satisfy the magic number rule of electrons, their stability can still be explained by superatomic orbital splitting. [16,22,23] Therefore, understanding the electronic structures of superatoms according to point group symmetry aids in knowing whether the properties of superatoms can conform to general fundamental laws and if the superatoms can be further regulated.…”

“…These calculated results are in accordance with group symmetry theory. [16,35] -12 As a molecule, if the superatom has 𝐼 ℎ symmetry, its 𝐹 SAMOs can be split into quadruple degenerate (𝐺u) orbitals and triple-degenerate (𝑇2u) [36] orbitals according to group symmetry theory. [35] Obviously, for a neutral C20 structure with 𝐷 3𝑑 symmetry, the lowest energy 𝐹 SAMOs are not quadruple degenerate.…”

Second-order superatoms: Au52-PAP featuring a three-dimensional cluster-of-clusters core

“…On such basis, we introduce the concept of second-order superatoms, whereby cluster aggregates show electronic shell characteristics similar to those of isolated superatoms and isolated atoms. 4,[43][44][45] Hence, second-order structures are species builtup from fusion or bonding of superatoms, whereas first-order species are superatoms composed from single atoms.…”