Study of the low-lying states of Ge2 and Ge−2 using negative ion zero electron kinetic energy spectroscopy

Abstract

The low-lying states of Ge2 and Ge−2 are probed using negative ion zero electron kinetic energy (ZEKE) spectroscopy. The ZEKE spectrum of Ge−2 yields an electron affinity of 2.035±0.001 eV for Ge2, as well as term energies and vibrational frequencies for the low-lying states of Ge−2 and Ge2. Specifically, we observe transitions originating from the anion 2Πu(3/2) ground state and 3Σ+g excited state (Te=279±10 cm−1) to several triplet and singlet states of Ge2. Term values and vibrational frequencies are determined for the Ge23Σ+g ground state, the low-lying 3Πu excited state (Te=337 cm−1 for the 2u spin–orbit component), and the somewhat higher lying 1Δg, 3Σ+g, and 1Πu states. We also determine the zero-field splitting for the X0+g and 1g components of the 3Σ+g state and the splittings between the 2u, 1u, and 0±u spin–orbit components of the 3Πu state. Detailed comparisons are made with Si2 and Si−2.