The structure of Au₆Y⁺ in the gas phase

The geometric and electronic structure of the Au₆Y⁺ cation is studied by gas phase vibrational spectroscopy combined with density functional theory calculations. The infrared photodissociation spectrum of Au₆Y⁺ Ne is measured in the 95–225 cm ⁻¹ energy range and exhibits two characteristic absorption bands at 181 cm ⁻¹ and 121 cm ⁻¹. Based on DFT/BP86 quantum chemical calculations, the infrared spectrum is assigned to the lowest energy species found, an eclipsed C3v geometry. The 3D structure of Au₆Y⁺ is considerably different from those previously found for both the neutral Au₆Y (quasi-planar circular geometry) and the anionic Au₆Y⁻ (planar D6h symmetry). The different geometries are related to different electronic structures in agreement with 2D and 3D phenomenological shell models for metal clusters