Probing the geometric and electronic structures of the lanthanide oxide HoO_n^-1/0 (n = 1-3) clusters

The complex 4f and 5d orbits of lanthanide oxide clusters increases the complexity and difficulty in both theoretical and experimental research. Combining the photoelectron imaging spectroscopy and ab initio calculations, the structural and electronic properties of HoO^- were studied. The adiabatic detachment energy (ADE) and vertical detachment energy (VDE) of HoO^- have been measured to be 1.31(3) eV and 1.42(2) eV, respectively. To determine the vibrational structure and observed spectral bands in the photoelectron spectrum, Franck-Condon simulation of the ground-state transition for HoO^- has been performed. The fundamental frequency of ground-state HoO is estimated to be 893 ± 73 cm^-1. Density functional method (DFT) was used to study the neutral and anionic clusters of HoO_n^-1/0 (n = 1-3), and the most stable cluster structures were obtained. Based on the DFT calculations, the theoretical ADEs and VDEs of anionic HoO_n^- (n = 1-3) clusters were obtained and the photoelectron spectra (PES) of HoO_n^- (n = 1-3) clusters were simulated, which might stimulate further experimental investigations on the Ho oxide clusters. In addition, the corresponding molecular orbitals (MOs) were also discussed to reveal the interaction between Ho and O atoms. This study can help us to understand the chemical bonding in Ho-containing molecules and will provide some light in their surface chemistry and photochemistry investigation.