Recent Publications

Export 8 results:
Sort by: Author Title Type [ Year  (Desc)]
2017
Kup Aylikci, N., J. M. Sampaio, A. Kahoul, V. Aylikci, İ. H. Karahan, M. Guerra, J. P. Santos, J. P. Marques, and E. Tirasoglu. "The investigation of K-shell fluorescence parameters of Zn-Fe alloys with different grain size and microstrain values." X-Ray Spectrometry 406 (2017): 1481-10. AbstractWebsite

It is known that zinc alloys with iron group metals have better corrosion resistance than pure zinc. Owing to the corrosion resistance of these alloys, Zn–Fe coatings are widely used in automotive industry...

2015
Diepold, Marc, Luis M. P. Fernandes, Jorge Machado, Pedro Amaro, Marwan Abdou-Ahmed, Fernando D. Amaro, Aldo Antognini, François Biraben, Tzu-Ling Chen, Daniel S. Covita, Andreas J. Dax, Beatrice Franke, Sandrine Galtier, Andrea L. Gouvea, Johannes Götzfried, Thomas Graf, Theodor W. Hänsch, Malte Hildebrandt, Paul Indelicato, Lucile Julien, Klaus Kirch, Andreas Knecht, Franz Kottmann, Julian J. Krauth, Yi-Wei Liu, Cristina M. B. Monteiro, Françoise Mulhauser, Boris Naar, Tobias Nebel, François Nez, Jose Paulo Santos, Joaquim M. F. dos Santos, Karsten Schuhmann, Csilla I. Szabo, David Taqqu, João F. C. A. Veloso, Andreas Voss, Birgit Weichelt, and Randolf Pohl. "Improved x-ray detection and particle identification with avalanche photodiodes." Review of Scientific Instruments 86 (2015): 053102-7. AbstractWebsite
n/a
2013
Szabo, C. I., P. Amaro, M. Guerra, J. P. Santos, A. Gumberidze, J. Attard, and P. Indelicato. "Ion temperature and x-ray line width measurements of highly charged argon ions in an ECR ion source." Physica Scripta T156 (2013): 014077. AbstractWebsite
n/a
Szabo, C. I., P. Amaro, M. Guerra, J. P. Santos, A. Gumberidze, J. Attard, and P. Indelicato. "Ion temperature and x-ray line width measurements of highly charged argon ions in an ECR ion source." Physica Scripta T156 (2013): 014077. AbstractWebsite
n/a
2008
Santos, J. P., and F. Parente. "Ionisation of phosphorus, arsenic, antimony, and bismuth by electron impact." The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics 47 (2008): 339-350. AbstractWebsite
Abstract.  Total ionization cross sections of neutral phosphorus, arsenic, antimony, and bismuth atoms by electron impact are reported and compared to the only available experimental results by Freund et al. [Phys. Rev. A 41, 3575 (1990)]. These calculations take into account the possibilities that some target atoms used in the experiments were in metastable states close to the ground state, the excitation-autoionization of nsnp4 excited states may be substantial, and the ions produced in experiments may be in excited, low-lying metastable states. The cross sections for direct ionization calculations are based on the BEB model by Kim and Rudd [Phys. Rev. A 50, 3954 (1994)]. Plane-wave Born cross sections scaled by the method developed by Kim [Phys. Rev. A 64, 3954 032713 (2001)] are used to determine the contributions from excitation-autoionization. The combination of the BEB model and the scaled Born cross sections is in agreement with the experimental data by Freund et al. These theoretical data are useful to experimentalists and can be used to complete data tables needed for plasma or astrophysical studies.
Santos, J. P., and F. Parente. "Ionisation of phosphorus, arsenic, antimony, and bismuth by electron impact." The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics 47 (2008): 339-350. AbstractWebsite

Abstract.  Total ionization cross sections of neutral phosphorus, arsenic, antimony, and bismuth atoms by electron impact are reported and compared to the only available experimental results by Freund et al. [Phys. Rev. A 41, 3575 (1990)]. These calculations take into account the possibilities that some target atoms used in the experiments were in metastable states close to the ground state, the excitation-autoionization of nsnp4 excited states may be substantial, and the ions produced in experiments may be in excited, low-lying metastable states. The cross sections for direct ionization calculations are based on the BEB model by Kim and Rudd [Phys. Rev. A 50, 3954 (1994)]. Plane-wave Born cross sections scaled by the method developed by Kim [Phys. Rev. A 64, 3954 032713 (2001)] are used to determine the contributions from excitation-autoionization. The combination of the BEB model and the scaled Born cross sections is in agreement with the experimental data by Freund et al. These theoretical data are useful to experimentalists and can be used to complete data tables needed for plasma or astrophysical studies.

2001
Martins, M. C., A. M. Costa, J. P. Santos, P. Indelicato, and F. Parente. "Interpretation of X-ray spectra emitted by Ar ions in an ECR ion source." Journal of Physics B: Atomic and Molecular Physics 34 (2001): 533-543. AbstractWebsite

We examine the most important processes leading to the creation of excited states from the ground configurations of Ar8+ to Ar16+ ions in an electron-cyclotron resonance ion source, which lead to the emission of K x-ray lines. Theoretical values for inner-shell excitation and ionization cross sections, including double KL ionization, transition probabilities and energies for the de-excitation processes, are calculated in the framework of the multi-configuration Dirac-Fock method. With reasonable assumptions about the electron energy distribution, a theoretical K x-ray spectrum is obtained, which reproduces very closely a recent experimental result.

Kim, Y. K., and P. M. Stone. "Ionization of boron, aluminum, gallium, and indium by electron impact." Physical Review A 64 (2001): 052707. AbstractWebsite

Measurements of electron impact ionization of neutral Al, Ga, and In show large cross sections compared to other elements in the same rows of the periodic table. Semiempirical and classical calculations of direct ionization cross sections are all substantially smaller. Calculations by McGuire [Phys. Rev. A 26, 125 (1982)] for aluminum that include excitations to autoionizing 3s3p2 doublet levels are 2.5 times higher than experiment at the peak. We report the direct ionization cross sections based on the binary-encounter-Bethe model of Kim and Rudd [Phys. Rev. A 50, 3954 (1994)], which is an ab initio theory. We add the autoionization contribution using scaled plane-wave Born cross sections as recently developed by Kim [Phys. Rev. A 64, 032713 (2001)] for excitations to the first set of autoionizing levels. Dirac-Fock wave functions are used for the atomic structure. Our results are in excellent agreement with experimental values and support substantial contributions from excitation-autoionization to the total ionization cross sections for these elements. We also compare the total ionization cross section of boron to available theories, though no experimental data are available.