A direct comparison between gas-phase and solid-state Hg 5d photoionization processes

We present an experimental study of the Hg 5d spin-orbit intensity branching ratio in the photon energy range 18–100 eV. The results obtained on cleaved α-HgS exhibit strong differences with respect to the recent gas-phase data by Shannon and Codling. This is the first time that $\text{experimental}$ results on gas-phase photoionization and $\text{experimental}$ results on solid-state photoionization of the same core levels are directly compared to each other. The evidence we provide for solid-state effects in the photoionization process is, therefore, independent of any particular theoretical interpretation of the data.