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1 pag., 1 fig. -- International Conference on Photonic, Electronic, and Atomic Collisions (ICPEAC) (30th. 2017. Cairns, Australia). -- Open Access funded by Creative Commons Atribution Licence 3.0, In the present study joint experimental and theoretical elastic differential cross sections for electron scattering from dichloromethane in the incident electron energy region 7 to 50eV are discussed.

Atomic data for electron impact ionization of all the elements from H to Ge are reviewed, the rates for these processes needing to be regularly updated following the publication of new experimental data and new theoretical calculations. Experimental cross sections, along with specific theoretical calculations when experimental data are missing, are fitted as functions of the electron energy, and from these fits ionization rate coefficients can be evaluated. It has been possible to take into account all elements but not all charge states of every element. Since the purpose of the paper is to update the ionization data evaluated and proposed in previous review papers, it is discussed if modifications are needed for the ions not considered. For highly ionized ions starting from the Ne- like iso- electronic sequence corrections do not appear necessary. On the other hand, except for Fe, for slightly ionized ions, specifically below the S- like iso- electronic sequence, the previously proposed data often underestimate the total ionization cross section, since only direct ionization channels have been considered and indirect processes have been neglected. Multiplicative correction coefficients are given to agree with recently published theoretical calculations. Experimental ionization data are considered, even when the presence of populated metastable levels ( related to the electron density inside the source) is reported in the ion beams involved in the cross- section data measurements. We deem such a procedure acceptable when the proposed rates have to be included in codes that simulate the impurity behaviour in magnetic- confinement fusion devices, i. e., when radial transport is added to ionization and recombination to predict spatially resolved charge- state distributions. On the other hand, for astrophysical plasmas the contributions of metastable levels to the experimental data may represent a serious problem since, generally, the values of the electron densities that are involved are much lower than those in the ion sources. However, we critically investigated this problem and we found that the presence of metastables does not significantly modify the rates of most of the ions apart from a dozen. For this set of ions we provide different, corrected rates. Recombination is not considered since a review has been recently published.

The O 1s excited states of formaldehyde have been investigated theoretically using the restricted open-shell Hartree-Fock method for electronic structure calculations and a linear vibronic coupling model for studying excited state nuclear dynamics. The results are compared with vibrationally resolved experimental data, published previously. In its 1B1(O 1s -> pi*) state the molecule is found to be unstable with respect to the out-of-plane bending mode v4(b1). The latter is a manifestation of vibronic coupling between the 1B1(O 1s -> pi*) state and the next excited state, 1A1(O 1s -> 3s). The dynamical calculations taking into account this interaction are in good agreement with experiment, whereas a simple Poisson intensity distribution reproduces only the main features of the spectral envelope of the 1B1(O 1s -> pi*) resonance. For the 1A1(O 1s -> 3s) state, the Poisson distribution gives poor agreement with experiment, whereas the vibronic coupling model yields a more satisfactory description.

Non-radiative transitions cause changes in the generation of the intensity of the L lines. In order to investigate the physical quantities relevant to the L lines affected by the non-radiative transitions, experimental measurements were carried out using a Si(Li) x-ray spectrometer. Atomic L shell Coster-Kronig yields (f(12), f(13) and f(23)) for some elements in the atomic number range 59 less than or equal to Z less than or equal to 90 were determined. These selected measured semi-empirical values were also fitted by least squares to polynomials in Z of the form Sigma (n) a(n) Z(n) (except for f(13)) and compared with theoretical and with earlier fitted values.

We report the observation of the unusually weak decay of the N 1s --> pi* core-excited N-2 molecule to the (B) over tilde (2)Sigma(u)(+) final state of N-2(+), which is only detectable in an exp ...

The near-edge x-ray absorption spectra of dinitrogen oxide and carbon dioxide have been measured with ultra high resolution and high statistical accuracy at the N 1s and O 1s edges, and at the C 1s and O 1s edges in N2O and CO2, respectively. The assignment of the peaks in the spectra is achieved via the analysis of the quantum defects of the Rydberg states, the use of the core-equivalent model and a comparison with previous photoabsorption and fragment ion spectra. New high-resolution spectra are provided for the O 1s excitations of CO2, and several new states are observed at the oxygen edge of N2O.

Resonant photofragmentation of core-excited methanol has been studied with high-resolution partial ion-yield spectroscopy near both the carbon and oxygen K-edge. Non-coincident and coincident fragmentation channels were monitored simultaneously. A steep increase in the coincidence yield curves above the ionization threshold, where the normal Auger decay produces doubly charged or multiply charged species which yield two or more charged fragments, has been observed. A relevant difference in resonant structure has been observed while comparing the fragmentation at the carbon K-edge and the oxygen K-edge. Evidence for inter-atomic Auger decay is presented for one particular single channel around the oxygen K-edge.

Measurements of the threshold photoelectron spectrum of helium have been made at the Gas Phase beamline at Elettra Synchrotron, Trieste. The energy region studied spans the thresholds of the HeC .N/ satellite states, beginning with N D 2, up to the He2C threshold. The energy resolution in the new spectrum is five times better than that of previous measurements and has enabled us to resolve satellite states with N D 13-19 for the first time. The part of the spectrum in the region of the double-ionization threshold exhibits a cusp-like feature in accordance with predictions of the Wannier model for threshold photo-double ionization. This region has been used to examine the role of doubly excited neutral states in single-ion formation and also to compare with previous experiments the ratio of the discrete and continuum amplitudes of the cusp. The use of the threshold photoelectron technique as an accurate and convenient method to calibrate the energy scales of optical monochromators for synchrotron radiation is noted.

We use a UV-pump/IR-probe scheme, combining a single attosecond UV pulse and a 750 nm IR pulse, to explore laser-assisted photoionization of the hydrogen molecule in the autoionization region. The electron energy distributions exhibit unusual streaking patterns that are explored for different angles of the electron ejection with respect to the polarization vector and the molecular axis. Moreover, by controlling the time delay between the pulses, we observe that one can suppress the autoionization channel.