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Fratini, F., L. Safari, P. Amaro, and J. P. Santos. "{Two-photon processes based on quantum commutators}." (2018): 1-13. Abstract
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Guerra, M., J. M. Sampaio, F. Parente, P. Indelicato, P. Hönicke, M. Muller, B. Beckhoff, J. P. Marques, and J. P. Santos. "{Theoretical and experimental determination of $K$- and $L$-shell x-ray relaxation parameters in Ni}." Phys. Rev. A 97 (2018): 042501. Abstract
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de J Mangueze, Adilson V., Maria F. G. Pessoa, Maria J. Silva, Alexis Ndayiragije, Hilário E. Magaia, Viriato S. I. Cossa, Fernando H. Reboredo, Maria L. Carvalho, José P. Santos, Mauro Guerra, ANA I. RIBEIRO-BARROS, Fernando C. Lidon, and José C. Ramalho. "{Simultaneous Zinc and selenium biofortification in rice. Accumulation, localization and implications on the overall mineral content of the flour}." Journal of Cereal Science 82 (2018): 34-41. Abstract
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LIDON, FERNANDO CEBOLA, KARLIANA OLIVEIRA, CARLOS GALHANO, Mauro Guerra, MARIA MANUELA RIBEIRO, JOÃO PELICA, INÊS PATACO, JOSÉ COCHICHO RAMALHO, ANTÓNIO EDUARDO LEITÃO, ANA SOFIA ALMEIDA, PAULA SCOTTI CAMPOS, Ana Ribeiro-Barros, ISABEL P. PAIS, Maria Manuela Silva, Maria Luisa Carvalho, Jose Paulo Santos, MARIA FERNANDA PESSOA, and FERNANDO HENRIQUE REBOREDO. "{SELENIUM BIOFORTIFICATION OF RICE THROUGH FOLIAR APPLICATION WITH SELENITE AND SELENATE}." Experimental Agriculture (2018): 1-15. Abstract

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Amaro, Pedro, Ulisses Loureiro, Laleh Safari, Filippo Fratini, Paul Indelicato, Thomas Stohlker, and Jose Paulo Santos. "{Quantum interference in laser spectroscopy of highly charged lithiumlike ions}." Phys. Rev. A 97 (2018): 022510. Abstract
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Monteiro, C. M. B., F. D. Amaro, M. S. Sousa, M. Abdou-Ahmed, P. Amaro, F. Biraben, T. Chen, D. S. Covita, A. J. Dax, M. Diepold, L. M. P. Fernandes, B. Franke, S. Galtier, A. L. Gouvêa, J. Götzfried, T. Graf, T. W. Hansch, M. Hildebrandt, P. Indelicato, L. Julien, K. Kirch, A. Knecht, F. Kottmann, J. J. Krauth, Y. Liu, J. Machado, F. Mulhauser, B. Naar, T. Nebel, F. Nez, R. Pohl, J. P. Santos, J. M. F. dos Santos, K. Schuhmann, C. I. Szabo, D. Taqqu, J. F. C. A. Veloso, and A. Antognini. "{On the double peak structure of avalanche photodiode response to monoenergetic x-rays at various temperatures and bias voltages}." J. Inst. 13 (2018): C01033. Abstract
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Machado, J., C. I. Szabo, J. P. Santos, P. Amaro, M. Guerra, A. Gumberidze, Guojie Bian, J. M. Isac, and P. Indelicato. "{High-precision measurements of $n=2\rightarrow n=1$ transition energies and level widths in He- and Be-like argon ions}." Phys. Rev. 97 (2018): 032517. Abstract
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Ménesguen, Y., M. - C. Lépy, J. M. Sampaio, J. P. Marques, F. Parente, M. Guerra, P. Indelicato, and J. P. Santos. "{Experimental and theoretical determination of the L-fluorescence yields of bismuth}." Metrologia 55 (2018): 621-630. Abstract
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Ménesguen, Y., M. - C. Lépy, J. M. Sampaio, J. P. Marques, F. Parente, M. Guerra, P. Indelicato, J. P. Santos, P. Hönicke, and B. Beckhoff. "{A combined experimental and theoretical approach to determine X-ray atomic fundamental quantities of tin}." X-Ray Spectrom. 47 (2018): 341-351. Abstract
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Santos, J. P., A. M. Costa, J. P. Marques, M. C. Martins, P. Indelicato, and F. Parente. "X-ray-spectroscopy analysis of electron-cyclotron-resonance ion-source plasmas." Physical Review A 82 (2010): 062516. AbstractWebsite
Analysis of x-ray spectra emitted by highly charged ions in an electron-cyclotron-resonance ion source (ECRIS) may be used as a tool to estimate the charge-state distribution (CSD) in the source plasma. For that purpose, knowledge of the electron energy distribution in the plasma, as well as the most important processes leading to the creation and de-excitation of ionic excited states are needed. In this work we present a method to estimate the ion CSD in an ECRIS through the analysis of the x-ray spectra emitted by the plasma. The method is applied to the analysis of a sulfur ECRIS plasma.
Santos, J. P., A. M. Costa, J. P. Marques, M. C. Martins, P. Indelicato, and F. Parente. "X-ray-spectroscopy analysis of electron-cyclotron-resonance ion-source plasmas." Physical Review A 82 (2010): 062516. AbstractWebsite

Analysis of x-ray spectra emitted by highly charged ions in an electron-cyclotron-resonance ion source (ECRIS) may be used as a tool to estimate the charge-state distribution (CSD) in the source plasma. For that purpose, knowledge of the electron energy distribution in the plasma, as well as the most important processes leading to the creation and de-excitation of ionic excited states are needed. In this work we present a method to estimate the ion CSD in an ECRIS through the analysis of the x-ray spectra emitted by the plasma. The method is applied to the analysis of a sulfur ECRIS plasma.

Santos, J. P., M. C. Martins, A. M. Costa, P. Indelicato, and F. Parente. "X-ray spectra emitted by Cl14+ ions in ECRIS plasmas." Vacuum 82 (2008): 1522-1524. AbstractWebsite
We study the contribution of the most important processes leading to the creation of excited states of Cl14+ ions from the ground configurations of Cl ions in an Electron Cyclotron Resonance Ion Source (ECRIS), which lead to the emission of K X-ray lines. Theoretical values for inner-shell excitation, K and KL ionization cross-sections, and energies and transition probabilities for the de-excitation processes are calculated in the framework of the Multi-Configuration Dirac-Fock (MCDF) method. With reasonable assumptions about the electron energy distribution, a theoretical K[alpha] X-ray spectrum is obtained, which reproduces closely a recent experimental result.
Santos, J. P., M. C. Martins, A. M. Costa, P. Indelicato, and F. Parente. "X-ray spectra emitted by Cl14+ ions in ECRIS plasmas." Vacuum 82 (2008): 1522-1524. AbstractWebsite

We study the contribution of the most important processes leading to the creation of excited states of Cl14+ ions from the ground configurations of Cl ions in an Electron Cyclotron Resonance Ion Source (ECRIS), which lead to the emission of K X-ray lines. Theoretical values for inner-shell excitation, K and KL ionization cross-sections, and energies and transition probabilities for the de-excitation processes are calculated in the framework of the Multi-Configuration Dirac-Fock (MCDF) method. With reasonable assumptions about the electron energy distribution, a theoretical K[alpha] X-ray spectrum is obtained, which reproduces closely a recent experimental result.

Santos, J. P., F. Parente, S. Boucard, and P. Indelicato. "X-ray energies of circular transitions in sigmonic atoms." Nuclear Instruments and Methods in Physics Research Section B 235 (2005): 206. AbstractWebsite
Energies of the circular (n, ℓ = n − 1) 1 less-than-or-equals, slant n less-than-or-equals, slant 20 levels have been calculated for hydrogenlike sigmonic atoms with 1 less-than-or-equals, slant Z less-than-or-equals, slant 92, using the current world average sigma mass, as well as the electronic shift in Σ− + Ne e− + nucleus systems, where Ne stands for the number of electrons. The electronic influence on sigmonic orbitals has also been investigated through the computation of the hyperfine structure and the anomalous Σ− magnetic moment effects in sigmonic Be 2p states.
Santos, J. P., F. Parente, S. Boucard, and P. Indelicato. "X-ray energies of circular transitions in sigmonic atoms." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 235 (2005): 206-209. AbstractWebsite

Energies of the circular (n, ℓ = n − 1) 1 less-than-or-equals, slant n less-than-or-equals, slant 20 levels have been calculated for hydrogenlike sigmonic atoms with 1 less-than-or-equals, slant Z less-than-or-equals, slant 92, using the current world average sigma mass, as well as the electronic shift in Σ− + Ne e− + nucleus systems, where Ne stands for the number of electrons. The electronic influence on sigmonic orbitals has also been investigated through the computation of the hyperfine structure and the anomalous Σ− magnetic moment effects in sigmonic Be 2p states.Exo

Santos, J. P., F. Parente, S. Boucard, P. Indelicato, and J. P. Desclaux. "X-ray energies of circular transitions and electrons screening in kaonic atoms." Physical Review A 71 (2005): 032501. AbstractWebsite
The QED contribution to the energies of the circular (n, = n–1), 2n13, transitions have been calculated for several kaonic atoms throughout the periodic table, using the current world-average kaon mass. Calculations were done in the framework of the Klein-Gordon equation, with finite nuclear size, finite particle size, and all-order Uelhing vacuum polarization corrections, as well as Källén and Sabry and Wichmann and Kroll corrections. These energy level values are compared with other computed values. The circular transition energies are compared with available measured and theoretical transition energies. Electron screening is evaluated using a Dirac-Fock model for the electronic part of the wave function. The effect of electronic wave-function correlation is evaluated.
Santos, J. P., F. Parente, S. Boucard, and J. P. Desclaux. "X-ray energies of circular transitions and electron screening in kaonic atoms." Physical Review A 71 (2005): 032501 EP -. AbstractWebsite

The QED contribution to the energies of the circular (n, = n–1), 2n13, transitions have been calculated for several kaonic atoms throughout the periodic table, using the current world-average kaon mass. Calculations were done in the framework of the Klein-Gordon equation, with finite nuclear size, finite particle size, and all-order Uelhing vacuum polarization corrections, as well as Källén and Sabry and Wichmann and Kroll corrections. These energy level values are compared with other computed values. The circular transition energies are compared with available measured and theoretical transition energies. Electron screening is evaluated using a Dirac-Fock model for the electronic part of the wave function. The effect of electronic wave-function correlation is evaluated.Exo

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Amaro, Pedro, Jose Paulo Santos, Ana Samouco, Ricardo Adão, Luís Souto Martins, Sebastian Weber, Stanislav Tashenov, Maria Luisa Carvalho, and Sofia Pessanha. "Validation of the Geant4 Monte Carlo package for X-ray fluorescence spectroscopy in triaxial geometry." Spectrochimica Acta Part B: Atomic Spectroscopy 130 (2017): 60-66. AbstractWebsite

Spectrochimica Acta Part B: Atomic Spectroscopy, 130 (2017) 60-66. doi:10.1016/j.sab.2017.02.012

Amaro, P., C. I. Szabo, S. Schlesser, A. Gumberidze, E. G. Kessler, A. Henins, E. O. Le Bigot, M. Trassinelli, J. M. Isac, P. Travers, M. Guerra, J. P. Santos, and P. Indelicato. "A vacuum double-crystal spectrometer for reference-free X-ray spectroscopy of highly charged ions." Radiation Physics and Chemistry 98 (2014): 132-149. AbstractWebsite

Radiation Physics and Chemistry, 98 + (2014) 132-149. doi:10.1016/j.radphyschem.2014.01.015

Amaro, P., C. I. Szabo, S. Schlesser, A. Gumberidze, E. G. Kessler, A. Henins, E. O. Le Bigot, M. Trassinelli, J. M. Isac, P. Travers, M. Guerra, J. P. Santos, and P. Indelicato. "A vacuum double-crystal spectrometer for reference-free X-ray spectroscopy of highly charged ions." Radiation Physics and Chemistry 98 (2014): 132-149. AbstractWebsite

Radiation Physics and Chemistry, 98 + (2014) 132-149. doi:10.1016/j.radphyschem.2014.01.015

Amaro, P., and Csilla I. Szabo. A vacuum double-crystal spectrometer for reference-free highly charged ions X-ray spectroscopy. Submitted to Radiation Physics and Chemistry, Radiat. Phys. Chem. ed., 2012. Abstract
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Manso, M., S. Pessanha, M. Guerra, J. L. Figueirinhas, J. P. Santos, and M. L. Carvalho. "Unveiling the Third Secret of Fátima: μ-XRF quantitative characterization and 2D elemental mapping." Spectrochimica Acta Part B: Atomic Spectroscopy 130 (2017): 35-38. AbstractWebsite

Spectrochimica Acta Part B: Atomic Spectroscopy, 130 (2017) 35-38. doi:10.1016/j.sab.2017.02.006

Guimarães, D., J. P. Santos, M. L. Carvalho, G. Vale, H. M. Santos, V. Geraldes, I. Rocha, and J. L. Capelo. "Ultrasonic energy as a tool to overcome some drawbacks in the determination of lead in brain tissue and urine of rats." Talanta 86 (2011): 442-446 . AbstractWebsite

An ultrasonic assisted solid‚Äìliquid extraction method was developed to determine the level of lead in the brain and urine of rats. Lead was determined by electrothermal atomic absorption spectrometry with longitudinal-Zeeman background correction. Several analytical drawbacks were addressed and overcome, namely small brain sample mass and the formation of precipitate in the urine samples. Utrasonication provided by an ultrasonic probe succeeded in extracting lead from brain samples. Furthermore, it was demonstrated that the formation of a precipitate lowered the lead content in the liquid phase of the urine. Lead was back extracted from the precipitate to the liquid phase with the aid of ultrasonic energy and acidifying the urine with 10% v/v nitric acid. A microwave-assisted acid digestion protocol was used to check the completeness of the lead extraction. The within bath and between bath precision was 5% (n = 9) and 7% (n = 3) respectively. The limit of quantification was 1.05 Œºg g‚àí1 for brain samples and 2.1 Œºg L‚àí1 for urine samples. A total of 6 samples of urine and 12 samples of brain from control rats and another 6 samples of urine and 12 samples of brain from rats fed with tap water rich in lead acetate were used in this research. Lead levels in brain and urine from exposed rats ranged from1.9 ¬± 0.2 Œºg g‚àí1 to 3.5 ¬± 0.2 Œºg g‚àí1 and from 752 ¬± 56 Œºg L‚àí1 to 60.9 ¬± 1.2 mg L‚àí1 respectively. Statistically significant differences of levels of lead in brain and urine were found between exposed and non exposed rats.

Guimarães, D., J. P. Santos, M. L. Carvalho, G. Vale, H. M. Santos, V. Geraldes, I. Rocha, and J. L. Capelo. "Ultrasonic energy as a tool to overcome some drawbacks in the determination of lead in brain tissue and urine of rats." Talanta 86 (2011): 442-446. AbstractWebsite

An ultrasonic assisted solid‚Äìliquid extraction method was developed to determine the level of lead in the brain and urine of rats. Lead was determined by electrothermal atomic absorption spectrometry with longitudinal-Zeeman background correction. Several analytical drawbacks were addressed and overcome, namely small brain sample mass and the formation of precipitate in the urine samples. Utrasonication provided by an ultrasonic probe succeeded in extracting lead from brain samples. Furthermore, it was demonstrated that the formation of a precipitate lowered the lead content in the liquid phase of the urine. Lead was back extracted from the precipitate to the liquid phase with the aid of ultrasonic energy and acidifying the urine with 10% v/v nitric acid. A microwave-assisted acid digestion protocol was used to check the completeness of the lead extraction. The within bath and between bath precision was 5% (n = 9) and 7% (n = 3) respectively. The limit of quantification was 1.05 Œºg g‚àí1 for brain samples and 2.1 Œºg L‚àí1 for urine samples. A total of 6 samples of urine and 12 samples of brain from control rats and another 6 samples of urine and 12 samples of brain from rats fed with tap water rich in lead acetate were used in this research. Lead levels in brain and urine from exposed rats ranged from1.9 ¬± 0.2 Œºg g‚àí1 to 3.5 ¬± 0.2 Œºg g‚àí1 and from 752 ¬± 56 Œºg L‚àí1 to 60.9 ¬± 1.2 mg L‚àí1 respectively. Statistically significant differences of levels of lead in brain and urine were found between exposed and non exposed rats.

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Surzhykov, A., P. Indelicato, J. P. Santos, P. Amaro, Th Stöhlker, and S. Fritzsche. "Two-photon absorption of few-electron heavy ions." Physical Review A 84 (2011): 022511. AbstractWebsite

The two-photon absorption of few-electron ions has been studied by using second-order perturbation theory and Dirac's relativistic equation. Within this framework, the general expressions for the excitation cross sections and rates are derived including a full account of the higher-order multipole terms in the expansion of the electron-photon interaction. While these expressions can be applied to any ion, independent of its particular shell structure, detailed computations are carried out for the two-photon absorption of hydrogen-, helium-, and berylliumlike ions and are compared with the available theoretical and experimental data. The importance of relativistic and nondipole effects in the analysis and computation of induced two-photon transitions is pointed out. Moreover, we discuss the potential of these transitions for atomic parity-violation studies in the high-Z domain.