Insights into the structure and growth of Lu-doped germanium clusters: comparing density functional theory calculations with photoelectron spectroscopy experiments

Abstract

ABSTRACT The structure and growth of a series of Lu-doped germanium clusters, LuGe n q (n = 2–14, q = 0, −1) have been investigated by previous photoelectron spectroscopy (PES) and density functional theory (DFT) calculations. The ground states of the anionic LuGe n – clusters obtained from DFT calculations are verified by comparing simulated PES with experimental results. The simulated PES for smaller clusters LuGe n – (n ≤ 6) display relatively simple spectral patterns, suggesting high symmetry structures. It is observed that the pentagonal bipyramid shape is the basic framework for the nascent growth process of LuGe n – (n = 2–8). The structures of LuGe n – (n = 2–13) clusters are all exohedral structures with the Lu atom adsorbed at the surface of the bare Ge n – clusters, while LuGe14 – is the smallest endohedral Lu-doped germanium cluster with the Lu atom completely fallen into the germanium frame. It is found that the LuGe n – clusters with even n are more stable than those with odd n and in the LuGe n clusters there is an opposite trend. Especially, the LuGe n q (n = 9, 12, q = 0, −1) clusters are extremely stable compared to other size clusters. HOMO–LUMO gap shows that the chemical stability of bare Ge n – (n = 2–14) clusters are stronger than that of LuGe n q (n = 2–14, q = 0, −1) clusters owing to the doping of a Lu atom.