Datensatz

Zusammenfassung

Within this thesis the dynamics of diatomic molecules, initiated and probed by intense extreme-ultraviolet (XUV) radiation delivered by the free-electron laser in Hamburg (FLASH), is investigated by means of three-dimensional recoil-ion momentum spectroscopy. In a study on iodine molecules I₂, ultrafast charge rearrangement between the two ions of a dissociating molecule is triggered by the localized absorption of short 87 eV XUV pulses at either of the ions and studied as a function of their internuclear distance. This yields the critical distance and the corresponding time up to which charge transfer along the internuclear axis can take place dependent on the charge state of the photonabsorbing ion. Additionally, the response to intense XUV radiation of molecules and of isolated atoms is compared, yielding that higher charge states are reached for the latter. The lifetime of interatomic Coulombic decay (ICD), an efficient relaxation mechanism in weakly bound systems, is determined for the (2s⁻¹) inner-valence vacancy of the neon dimer Ne₂. Applying an XUV pump-probe scheme at a photon energy of 58 eV, the dynamics of ICD is for the first time traced directly. The measured lifetime of (150 ± 50) fs only agrees well with predictions that explicitly take nuclear dynamics prior to the decay into account, demonstrating the key role of the motion for ICD in light systems.