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Abstract: By combining multi-particle coincidence detection of electrons and ions with ionisation by soft X-ray synchrotron radiation we demonstrate an effective tool for atomic spectroscopy and site-specific photochemistry. Its most novel capability is application to molecular fragmentation after K-shell vacancy production in atoms distinguished only by their chemical environment. [Copyright &y& Elsevier]

Abstract: The inner valence electron spectrum of the CS2 molecule has been investigated in the binding energy range between 18.6 and 26.3eV using synchrotron radiation for ionisation. Photon energies in the range from 67 to about 167eV have been used, with particular focus on 166.70, 166.89 and 167.09eV for which S2p electrons are resonantly transferred into Rydberg orbitals close to the ionisation threshold. From there, autoionisation takes the molecule into various cationic states characterized by two valence holes and a Rydberg spectator electron. Many new bands are observed which contain vibrational progressions with spacings around 120meV in most cases. These are assigned as excitations of the totally symmetric stretching ν 1 mode in the cationic state. The new bands reflect states in the cation that are close to the electronic states of the dication and assignments are made by comparison to double ionisation electron spectra. [Copyright &y& Elsevier]

Single-photon multiple ionization processes of acetaldehyde (ethanal) have been experimentally investigated by utilizing a multi-particle coincidence technique based on the time-of-flight magnetic bottle principle, in combination with either a synchrotron radiation source or a pulsed helium discharge lamp. The processes investigated include double and triple ionization in the valence region as well as single and double Auger decay of core-ionized acetaldehyde. The latter are studied site-selectively for chemically different carbon core vacancies, scrutinizing early theoretical predictions specifically made for the case of acetaldehyde. Moreover, Auger processes in shake-up and core-valence ionized states are investigated. In the cases where the processes involve simultaneous emission of two electrons, the distributions of the energy sharing are presented, emphasizing either the knock-out or shake-off mechanism. [ABSTRACT FROM AUTHOR]