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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., Chintan Shah, José Crespo R. López-Urrutia, Ming Feng Gu, Thomas Pfeifer, José Marques, Filipe Grilo, José Paulo Santos, and Pedro Amaro. "Revisiting the Fe xvii Line Emission Problem: Laboratory Measurements of the 3s–2p and 3d–2p Line-formation Channels." The Astrophysical Journal (2019). AbstractWebsite
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Santos, J. P., A. M. Costa, M. C. Martins, F. Parente, and P. Indelicato. "Modeling praseodymium K X-ray lines in an electron beam ion trap." Eur. Phys. J. D 66 (2012): 202. AbstractWebsite

We study the most important processes for the creation of excited states in He-like through C- like praseodymium ions from the ions ground configurations, leading to the emission of K X-ray lines. Theoretical values for inner-shell excitation and ionization cross sections, transition probabilities and energies for the deexcitation processes, are calculated in the framework of the multi-configuration Dirac- Fock method, including QED corrections. Using these calculated values, a theoretical Kα X-ray spectrum is obtained, which is compared to recent experimental data obtained in the Livermore Super-EBIT electron beam ion trap facility.

Santos, Jose Paulo, Maria Conceição Martins, Ana Maria Costa, José Pires Marques, Paul Indelicato, and Fernando Parente. "Theoretical determination of K X-ray transition energy and probability values for highly charged ions of lanthanum and cerium." The European Physical Journal D 68 (2014): 244. AbstractWebsite
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Santos, J. P., G. C. Rodrigues, J. P. Marques, F. Parente, J. P. Desclaux, and P. Indelicato. "Relativistic correlation correction to the binding energies of the ground configuration of beryllium-like, neon-like, magnesium-like and argon-like ions." The European Physical Journal D 37 (2006): 201-207. AbstractWebsite
Total electronic correlation corrections to the binding energies of the isoelectronic series of beryllium, neon, magnesium and argon, are calculated in the framework of relativistic multiconfiguration Dirac-Fock method. Convergence of the correlation energies is studied as the active set of orbitals is increased. The Breit interaction is treated fully self-consistently. The final results can be used in the accurately determination of atomic masses from highly charged ions data obtained in Penning-trap experiments.
Santos, J. P., F. Mota-Furtado, M. F. Laranjeira, and F. Parente. "Rydberg states of atoms in parallel electric and magnetic fields." Physical Review A 59 (1999): 1703-1706. AbstractWebsite

We present theoretical results for the photoabsorption spectrum of an atom in parallel electric and magnetic fields, using the R-matrix method combined with quantum-defect theory. We introduce a radial basis set which is complete and orthonormal over a semi-infinite interval [r0,(infinity)), to allow calculations to be performed for high Rydberg states in nonhydrogenic atoms without encountering problems due to linear dependence of the basis set. The nonhydrogenic character of the spectra is analyzed for Li and Rb, and a comparison is made with previous high-precision experiments which shows that the theoretical results agree very well with experiment.

Santos, J. P., M. L. Costa, R. I. Olariu, and F. Parente. "Theoretical study of the molecular properties of benzyl azide, 2-, 3- and 4-methyl benzyl azide." The European Physical Journal D - Atomic, Molecular and Optical Physics 39 (2006): 379-384. AbstractWebsite

Ab initio and density functional calculations have been performed to study the benzyl azide, 2-, 3- and 4-methyl benzyl azides. Several molecular properties, such as conformational equilibrium, optimal geometry, and vibrational frequencies, have been computed for these molecules. Ionisation energies were also computed.

Santos, J. P., M. L. Costa, R. I. Olariu, and F. Parente. "Theoretical study of the molecular properties of benzyl azide, 2-, 3- and 4-methyl benzyl azide." The European Physical Journal D - Atomic, Molecular and Optical Physics 39 (2006): 379-384. AbstractWebsite
Ab initio and density functional calculations have been performed to study the benzyl azide, 2-, 3- and 4-methyl benzyl azides. Several molecular properties, such as conformational equilibrium, optimal geometry, and vibrational frequencies, have been computed for these molecules. Ionisation energies were also computed.
Santos, J. P., J. P. Marques, F. Parente, P. Indelicato, and J. P. Desclaux. "Relativistic 2s1/2 (L1) atomic subshell radiationless transition probabilities for Yb and Hg." Atomic Data and Nuclear Data Tables 76 (2000): 49-69. Abstract

Radiationless transition rates to L1 vacancy states have been calculated ab initio in the Dirac-Fock approximation. The calculations include quantum-electrodynamic corrections. Results in the jj coupling scheme for all possible L1 transitions are tabulated for elements Yb and Hg.

Santos, J. P., and M. F. Laranjeira. Métodos Matemáticos para Físicos e Engenheiros., 2004. Abstract
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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., J. P. Marques, F. Parente, E. Lindroth, P. Indelicato, and J. P. Desclaux. "Relativistic 2s1/2 (L1) atomic subshell decay rates and fluorescence yields for Yb and Hg." Journal of Physics B: Atomic and Molecular Physics 32 (1999): 2089. AbstractWebsite
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Santos, J., A. Costa, C. Madruga, F. Parente, and P. Indelicato. "Relativistic transition wavelenghts and probabilities for spectral lines of Ne II." The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics 63 (2011): 89-96. AbstractWebsite

Transition wavelengths and probabilities for several 2 p 4 3 p -2 p 4 3 s and 2 p 4 3 d -2 p 4 3 p lines in fluorine-like neon ion (NeII) have been calculated within the multiconfiguration Dirac-Fock (MCDF) method with quantum electrodynamics (QED) corrections. The results are compared with all existing experimental and theoretical data.

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

Santos, S. C. P. L., M. E. Cruz, A. M. E. Barroso, C. P. S. Fonseca, M. Guerra, M. L. Carvalho, and J. P. Santos. "Elemental characterization of plants and soils in Panasqueira tungsten mining region." Journal of Soils Sediments 14 (2014): 778. AbstractWebsite

... Title Elemental characterization of plants and soils in Panasqueira tungsten mining region Journal Journal of Soils and Sediments Volume 14, Issue 4 , pp 778-784 Cover Date 2014-04-01 DOI 10.1007 / s11368 - 013 - 0788 - x Print ISSN 1439-0108 Online ISSN 1614-7480 ...

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, S. C. P. L., M. E. Cruz, A. M. E. Barroso, C. P. S. Fonseca, M. Guerra, M. L. Carvalho, and J. P. Santos. "Elemental characterization of plants and soils in Panasqueira tungsten mining region." Journal of Soils Sediments 14 (2014): 778. AbstractWebsite

... Title Elemental characterization of plants and soils in Panasqueira tungsten mining region Journal Journal of Soils and Sediments Volume 14, Issue 4 , pp 778-784 Cover Date 2014-04-01 DOI 10.1007 / s11368 - 013 - 0788 - x Print ISSN 1439-0108 Online ISSN 1614-7480 ...

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., 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., Iulian Otel, Joao Silveira, Valentina Vassilenko, António Mata, Maria Luísa Carvalho, José Paulo Santos, and Sofia Pessanha. "Application of Unsupervised Multivariate Analysis Methods to Raman Spectroscopic Assessment of Human Dental Enamel." Computers (2021). AbstractWebsite
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Silva, A. L. M., S. Cirino, M. L. Carvalho, M. Manso, S. Pessanha, C. D. R. Azevedo, L. F. N. D. Carramate, J. P. Santos, M. Guerra, and J. F. C. A. Veloso. "Elemental mapping in a contemporary miniature by full-field X-ray fluorescence imaging with gaseous detector vs. scanning X-ray fluorescence imaging with polycapillary optics." (2017): 1-7. Abstract

Spectrochimica Acta Part B: Atomic Spectroscopy, 129 (2016) 1-7. doi:10.1016/j.sab.2016.12.006

Surzhykov, A., A. Volotka, F. Fratini, J. P. Santos, P. Indelicato, G. Plunien, Th Stöhlker, and S. Fritzsche. "Angular correlations in the two-photon decay of heliumlike heavy ions." Physical Review A 81 (2010): 042510. AbstractWebsite
The two-photon decay of heavy, helium-like ions is investigated based on second-order perturbation theory and Dirac’s relativistic equation. Special attention has been paid to the angular emission of the two photons (i.e., how the angular correlation function depends on the shell structure of the ions in their initial and final states). Moreover, the effects from the (electric and magnetic) nondipole terms in the expansion of the electron-photon interaction are discussed. Detailed calculations have been carried out for the two-photon decay of the 1s2s1S0, 1s2s3S1, and 1s2p3P0 states of helium-like Xe52+, Au77+, and U90+ ions.