All-electron spin-orbit configuration interaction study on the valence and low-lying Rydberg electronic states of GeH

- The PECs of GeH were computed with the MRCI method.
- The spin-orbit coupling effect was considered in the calculations.
- The spectroscopic constants of Λ-S and Ω states of GeH were fitted.
- The predissociation mechanisms of A2Δ, 22Σ+ and 32Σ+ states were discussed.
- The radiative lifetimes of A2Δ and a4Σ− states of GeH were evaluated.

Germanium monohydride (GeH), an important radical for the growth of semiconductor germanium film, has received much attention. However, the electronic structure and spectroscopic properties of low-lying excited states of the radical have not been well understood, especially the coupling between different electronic states. In this work, eight Λ-S valence states and four low-lying Λ-S Rydberg states correlated to the four lowest dissociation limits of GeH are investigated by employing the multireference configuration interaction method. With the inclusion of spin-orbit coupling effect, there are 24 Ω states generated from 12 Λ-S states. On the basis of computed potential energy curves of the Λ-S and Ω states, the spectroscopic parameters of bound states are evaluated, which demonstrate that the first Rydberg state 32Σ+ located at 5.12 eV is exactly the B2Σ+ state tentatively assigned by experiment. With the help of the calculated spin-orbit matrix elements, the predissociation mechanism of A2Δ state is investigated, which may interpret the fact that ν′>2 vibrational levels of A2Δ state are difficult to be detected in experiment. Finally, the transition dipole moments and the radiative lifetimes of several vibrational levels of A2Δ and a4Σ− states are calculated.