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Guerra, M., P. Amaro, C. I. Szabo, A. Gumberidze, P. Indelicato, and J. P. Santos. "Analysis of the charge state distribution in an ECRIS Ar plasma using high-resolution x-ray spectra." Journal of Physics B: Atomic, Molecular and Optical Physics 46 (2013): 065701. AbstractWebsite

In this work, we obtained a charge state distribution inside an Ar plasma produced by an electron–cyclotron-resonance ion source. The processes that lead to the observed lines in x-ray spectra are identified and included in the simulated x-ray spectrum. The geometrical constraints of the flat double crystal spectrometer, used to measure the x-ray spectrum, are investigated as they are crucial for correctly obtaining the ion densities from the observed transition amplitudes. Multiple electron impact ionization is included, and a realistic electron velocity distribution is taken into account. The charge state distribution of the Ar ions is compared to measured extracted ionic currents.

Guerra, M., F. Parente, P. Indelicato, and J. P. Santos. "Modified binary encounter Bethe model for electron-impact ionization." Int. J. Mass Spectrom. 313 (2012): 1. AbstractWebsite

Theoretical expressions for ionization cross sections by electron impact based on the binary encounter Bethe (BEB) model, valid from ionization threshold up to relativistic energies, are proposed.
The new modified BEB (MBEB) and its relativistic counterpart (MRBEB) expressions are simpler than the BEB (nonrelativistic and relativistic) expressions because they require only one atomic parameter, namely the binding energy of the electrons to be ionized, and use only one scaling term for the ionization of all sub-shells.
The new models are used to calculate the K-, L- and M-shell ionization cross sections by electron impact for several atoms with Z from 6 to 83. Comparisons with all, to the best of our knowledge, available experimental data show that this model is as good or better than other models, with less complexity.

Guerra, M., J. M. Sampaio, T. I. Madeira, F. Parente, P. Indelicato, J. P. Marques, J. P. Santos, J. Hoszowska, Cl J. Dousse, L. Loperetti, F. Zeeshan, M. Muller, R. Unterumsberger, and B. Beckhoff. "Theoretical and experimental determination of L-shell decay rates, line widths, and fluorescence yields in Ge." Physical Review A 92 (2015): 022507-9. AbstractWebsite
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Guerra, M., F. Parente, and J. P. Santos. "Electron impact ionization of atomic target inner-shells." Journal of Physics: Conference Series 194 (2009): 042047. AbstractWebsite
There is a need for reliable theoretical methods to calculate electron-impact total ionization cross sections for the large number of neutral atoms and ions with open shell structures. These cross sections are used in a wide range of scientific and industrial applications, such as astrophysical plasmas, atmospheric science, X-ray lasers, magnetic fusion, radiation physics, semiconductor fabrication, accelerator physics and tumor therapy physics. The binary-encounter-Bethe (BEB) model [1], using an analytic formula that requires only two atomic constants, the binding energy and kinetic energy of the electrons, generates direct ionization cross sections for any neutral atom (or molecule), which are reliable in intensity (15%) and shape from the ionization threshold to a few keV in the incident energy [3], or to thousands keV if we consider its relativistic version(RBEB) [2]. In this work we present K- and L-shell ionization cross sections calculations for heavy atoms.
Guerra, M., P. Amaro, J. Machado, and J. P. Santos. "Modified Binary-Encounter-Bethe Model for Electron Impact Ionization Cross Sections of Highly Charged Ions ." Journal of Physics: Conference Series 635 (2015): 052067. AbstractWebsite
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Guerra, M., F. Parente, and J. P. Santos. "Electron impact ionization of atomic target inner-shells." Journal of Physics: Conference Series 194 (2009): 042047. AbstractWebsite

There is a need for reliable theoretical methods to calculate electron-impact total ionization cross sections for the large number of neutral atoms and ions with open shell structures. These cross sections are used in a wide range of scientific and industrial applications, such as astrophysical plasmas, atmospheric science, X-ray lasers, magnetic fusion, radiation physics, semiconductor fabrication, accelerator physics and tumor therapy physics. The binary-encounter-Bethe (BEB) model [1], using an analytic formula that requires only two atomic constants, the binding energy and kinetic energy of the electrons, generates direct ionization cross sections for any neutral atom (or molecule), which are reliable in intensity (15%) and shape from the ionization threshold to a few keV in the incident energy [3], or to thousands keV if we consider its relativistic version(RBEB) [2]. In this work we present K- and L-shell ionization cross sections calculations for heavy atoms.

Guerra, M., F. Parente, and J. P. Santos. "Electron impact ionization cross sections of several ionization stages of Kr, Ar and Fe." International Journal of Mass Spectrometry 348 (2013): 1-8. AbstractWebsite

International Journal of Mass Spectrometry, 348 (2013) 1-8. doi:10.1016/j.ijms.2013.02.011

Grilo, Filipe, Chintan Shah, Steffen Kühn, René Steinbrügge, Keisuke Fujii, José Marques, Ming Feng Gu, José Paulo Santos, José Crespo R. López-Urrutia, and Pedro Amaro. "Comprehensive Laboratory Measurements Resolving the {LMM} Dielectronic Recombination Satellite Lines in Ne-like Fe xvii Ions." The Astrophysical Journal 913 (2021): 140. AbstractWebsite
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