X-ray spectroscopy on diatomic and cationic molecules

X-ray spectroscopy have been used to study the electronic structure of diatomic and cationic molecules. X-ray absorption spectra of the molecular cations N 2 + , O 2 + , and CO + have been measured. The spectra are vibrationally resolved and are analyzed with theoretical and semi-empirical methods determining spectroscopic constants of core-excited states. Ionization of water have been studied by time resolved X-ray absorption spectroscopy. The evolution of the absorption spectrum gives an estimate of the formation time of the aqueous hydroxyl radical and an estimate of the upper limit of the lifetime of H 2 O + . The aqueous hydroxyl radical has been studied by resonant inelastic X-ray scattering. The experiment is suggesting that the electronic structure of the OH-radical is not heavily affected upon solvation. Resonant inelastic X-ray scattering spectra at the π*-resonance of N 2 have been recorded and are analyzed within the Kramers-Heisenberg framework, emphasizing the importance of lifetime-vibrational interference. The spectra of N 2 show states populated by radiative electron rearrangement and due to their repulsiveness the features images the vibrational wavefunctions of the intermediate state.