Spatio-Temporal Dynamical Systems in Inner-Shell Photoionization in Free Molecules,Clusters, and Solids

Dynamic spatial hole localization and symmetry breaking phenomena are examined. Absorption of X-ray synchrotron and free-electron–laser radiation in matter is accompanied by strong dynamic corehole localization and temporary trap of the electron ejected from a deep level within the finite size potential barrier. As a result the symmetry of core excited states is reduced in comparison with ground state as the inversion symmetry is being broken. This is a very general property of coreexcited polyatomic compounds with equivalent atoms as their equivalence implies their equal probability of excitation averaged over large timescale but not simultaneous core excitation. Different approaches to rationalizing the symmetry breaking phenomena are presented and discussed with the emphasis on the quasiatomic dynamic corehole localization model. By examining the experimental ultrafast probe of photoabsorption processes we demonstrate an important role of spatio-temporal (nanometric-femtosecond) dynamically localized coreexcited moieties in molecule, clusters and solids. The photoelectron angular distributions from N and O 1s levels in fixed-in-space N₂ and CO₂ molecules, the photoelectron induced rotational heating of N₂, the Auger decay spectra of N₂ and the near S 1s edge X-ray absorption fine structure of free SF₆ molecules are discussed in more detail.