Probing the structural and electronic properties of Al-doped small niobium clusters

► The dopant atom does significantly perturb the atomic structures of pure niobium cluster anions. ► The dopant atom always occupies the surface of bimetallic clusters. ► Generalized Koopmans' theorem is applied to predict the vertical electron detachment energies. ► The photoelectron spectra are simulated to compare with the experimental results.