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The photodouble ionization of water at about 32 eV excess energy has been investigated both experimentally and theoretically. In an energy and angular resolved photoelectron–photoelectron coincidence experiment, the two photoelectrons in unequal energy sharing (25 and 7 eV) condition, have been detected in a plane perpendicular to the propagation direction of the linearly polarized radiation. The measured angular distributions have been compared with, molecular orientation averaged, triple differential cross sections calculated with a recently developed theoretical model (Randazzo et al 2020 Phys. Rev. A 101 033407). The model uses separable products of orbitals as initial electronic state of the water molecule taken as a two-electron target and describes accurately the correlated two electron continuum. The combination of calculated cross sections corresponding to different dication states capture most of the measured features in terms of the evolution of both the shape and the intensity as a function of the faster electron direction which is set at 0°, 30° and 60° with respect to the polarization vector ε ⃗ of the incident radiation. A detailed analysis in terms of the different dication states as well as of the partial wave contributions to the electron pair wave function sheds light on the origin of such features.

Photoelectron spectroscopy, mass spectrometry and electron–ion coincidence experiments combined with tunable synchrotron radiation have been used to study the decay and fragmentation of 2Cl-pyrimidine after Cl(2p), C(1s) and N(1s) excitations. The goal is to investigate how the state- and site-selected excitation and the chemical environment affect the fragmentation paths of the molecule and to make a comparison with fragmentation induced by direct valence ionization. It has been found that the site-selective inner shell excitation affects the branching ratio of the fragments, while the particular fragmentation channels of the cation are determined by the final state populated in the resonant decay of the core excited states. Effects of nuclear motion in the core excited states and the possible ultrafast molecular dissociation following the Cl(2p → σ *) core excitation are discussed.

The photoionization of the ground state and 6p laser-excited caesium atoms was studied above their 4d ionization thresholds. The 4d photoelectron spectrum of 6p laser-excited atoms shows a stronger excitation of satellites upon ionization than its ground state counterpart. The relative intensities of satellite and main photolines show a slow variation with the incoming photon energy for both the ground state and the 6p laser-excited states. An assignment of the excited state spectra, supported by recently published ground state photoionization spectra and calculations, is given and a preliminary analysis of the 4d Auger spectrum of laser-excited atoms is also presented.

This paper reports a study by ion and electron spectroscopy of two-photon excited resonances of Cs and Rb at the 4d and 3d edges, respectively. The experimental spectra were simulated using multiconfiguration Dirac–Fock calculations. The excitation spectrum of laser-excited Cs atoms is predicted by single configuration calculations whereas a large set of correlated configurations is needed for proper description of the core-excitation of laser-excited Rb atoms.

We have measured the NEXAFS spectrum and the relative photoionization cross section of the 3d spin - orbit components of the barium atom in the energy range up to 50 eV above the ionization threshold. As in Xe and Cs, also in barium the two spin - orbit components show strongly different energy dependence. A strong enhancement of the 3d(5/2) cross section near the 3d(3/2) ionization threshold, which is attributed to interchannel coupling, is observed. The experimental results are in good agreement with the relativistic time- dependent density functional theory calculations.

The ionization cross-section of the 3d spin–orbit components of the Cs atom has been measured from about 12 to 70 eV above their respective thresholds. The measured relative ionization cross-section of the 3d5/2 channel exhibits a pronounced minimum above threshold followed by a second maximum near the 3d3/2 ionization onset and thus qualitatively confirms the theoretical predictions of a spin–orbit activated interchannel coupling (Amusia et al 2002 Phys. Rev. Lett 88 093002).