On the theory of double ICD and applications of ICD

Interatomic or intermolecular Coulombic decay (ICD) is an efficient relaxation pathway on the femtosecond timescale, where after inner-valence ionization of an atom or molecule, the initial vacancy is filled by an outer-valence electron and the excess energy is transferred radiationlessly to its neighbor, leading to its ionization. In this thesis, ICD-related phenomena are studied. Therefore, the work is divided into two main parts. Part I treats the new decay channel double ICD (dICD), where after the relaxation of the system, the excess energy exceeds the double ionization threshold of the neighboring species, resulting in its double ionization. We derive an asymptotic and perturbative expression for the dICD decay width as an indicator of efficiency. In Part II, nuclear dynamics during ICD and pre-ICD in NeKr and Ar${}_2$ dimers are investigated focusing on different aspects. In pre-ICD, the excess energy is only sufficient for the excitation of the neighboring atom or molecule and additional energy has to be provided for its ionization. While the study about NeKr dimers undergoing ICD mostly concentrates on interference effects, the main goal of the pre-ICD in Ar${}_2$ dimers study is to understand the nuclear motions and their appearance in the corresponding spectrum.