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Abstract

Within the framework of this thesis a method for break-up channel specific detection of the photoelectrons from photon-induced dissociation processes of fast moving molecular ion has been established. For this purpose, a novel saddlepoint electron spectrometer was commissioned while investigating the photodetachment dynamics on a fast moving beam of oxygen anions. For a complete detection of all outgoing reaction products emerging from the photolysis of small water clusters (H₂O) _nH⁺ (n ≤ 3) in the wavelength range of 13.5-40 nm a new fragment analyzing system has been developed and, in combination with the novel saddle-point spectrometer applied, to investigate the dissociative photoionization of the hydronium (H₃O⁺) and the Zundel ion (H₅O₂ ⁺). In case of the hydronium ion, a binary H₂O⁺ + H⁺ and two three-body channels OH⁺ +2H⁺, OH⁺ +H⁺ +H have been identified to be initiated by outer valence vacancies where the binary channel is mainly triggered by the ionization of the 3a₁ orbital and the three-body channels follow ionization from the 1e₁ orbital. The photolysis of H₅O₂ ⁺ is found to proceed via five prominent pathways where for a large number of processes the hydronium ion is split off as a stable structural unit. Also here, the investigation of the photoelectron spectra revealed the prominent dissociation pathways to be initiated by outer valence vacancies.