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Inner-shell photoabsorption by a high-Z atom typically results in a sequence of electronic relaxation processes involving both, inner-shell and valence electrons. In the molecular environment the induced positive charge, initially localized on the absorbing atom, can be later redistributed over the whole molecular system. Electronic relaxation involving delocalized valence electrons, nuclear dissociation dynamics and, in case of intense ionizing radiation, multiple photoabsorption often proceed on the same time scale (a few fs), resulting in a variety of interweaved fragmentation pathways. Here these phenomena will be discussed in relation to a series of recent LCLS experiments on X-ray ionization and fragmentation of small polyatomic molecules containing one heavy atom with high absorption cross section. In particular, charge redistribution mechanisms, role of the interatomic processes and their dependence on the internuclear distance will be addressed.
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