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Moser, I., F. Mota-Furtado, P. F. O'Mahony, and J. P. Santos. "Rydberg wave packets in parallel electric and magnetic fields." Physical Review A 55 (1997): 3724-3729. Abstract

The magnitude of the time autocorrelation function M between states excited by two Gaussian laser pulses is calculated for both hydrogen and rubidium atoms inparallel electric and magnetic fields. M is determined by a full quantum-mechanical calculation but the peaks are identified with the periods of the shortest periodicorbits of the corresponding classical system. Qualitative agreement is obtained with experimental results, however, discrepancies are found in the relative heights ofthe peaks.

Morrison, J. C., S. Boyd, L. Marsano, B. Bialecki, T. Ericsson, and J. P. Santos. "Numerical methods for solving the Hartree-Fock equations of diatomic molecules I." Communications in Computational Physics 5 (2008): 959-985. AbstractWebsite
The theory of domain decomposition is described and used to divide the variable domain of a diatomic molecule into separate regions which are solved independently. This approach makes it possible to use fast Krylov methods in the broad interior of the region while using explicit methods such as Gaussian elimination on the boundaries. As is demonstrated by solving a number of model problems, these methods enable one to obtain solutions of the relevant partial differential equations and eigenvalue equations accurate to six significant figures with a small amount of computational time. Since the numerical approach described in this article decomposes the variable space into separate regions where the equations are solved independently, our approach is very well-suited to parallel computing and offers the long term possibility of studying complex molecules by dividing them into smaller fragments that are calculated separately.
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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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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Ménesguen, Y., {M. C. } Lépy, Y. Ito, M. Yamashita, S. Fukushima, M. Polasik, K. Słabkowska, Syrocki, E. Wȩder, P. Indelicato, {J. P. } Marques, {J. M. } Sampaio, M. Guerra, F. Parente, and {J. P. } Santos. "Precise x-ray energies of gadolinium determined by a combined experimental and theoretical approach." Journal Of Quantitative Spectroscopy & Radiative Transfer 236 (2019). Abstract

We combined different experimental techniques with a theoretical approach to determine a consistent set of diagram lines energies and binding energies. We propose an original approach consisting in determining the mass attenuation coefficients in an energy range covering the L-, M- and N- absorption edges, including a detailed evaluation of the associated uncertainties, to derive precisely the binding energies. We investigated the Lα, Lβ and M spectra of Gd with an independantly calibrated high-resolution anti-parallel double-crystal x-ray spectrometer. All the lines were identified and found in excellent agreement with the binding energies previously derived. Morever, we identified for the first time M5−O2, M4−O2,3 and M4−N2,3 diagram lines.

Mayo, R., M. Ortiz, F. Parente, and J. P. Santos. "Experimental and theoretical transition probabilities for lines arising from the 6p configurations of Au II." Journal of Physics B: Atomic, Molecular and Optical Physics 40 (2007): 4651. AbstractWebsite

Experimental relative transition probabilities for the 16 more pro-eminent lines arising from the 6p configurations of Au II were determined from the emission-line intensities in a laser-produced plasma. The experiment was carried out using a Cu-Au alloy with 10% Au content in order to obtain an optically thin plasma. Transition probabilities were placed on an absolute scale by using theoretical lifetimes calculated in this work, line-strength sum rules and Boltzmann plot. A comparison has been conducted between present experimental results, the theoretical data available and new calculations with the multi-configuration Dirac-Fock method reported in this work, as well as a study of the plasma conditions.

Mayo, R., M. Ortiz, F. Parente, and J. P. Santos. "Experimental and theoretical transition probabilities for lines arising from the 6p configurations of Au II." Journal of Physics B: Atomic, Molecular and Optical Physics 40 (2007): 4651. AbstractWebsite
Experimental relative transition probabilities for the 16 more pro-eminent lines arising from the 6p configurations of Au II were determined from the emission-line intensities in a laser-produced plasma. The experiment was carried out using a Cu-Au alloy with 10% Au content in order to obtain an optically thin plasma. Transition probabilities were placed on an absolute scale by using theoretical lifetimes calculated in this work, line-strength sum rules and Boltzmann plot. A comparison has been conducted between present experimental results, the theoretical data available and new calculations with the multi-configuration Dirac-Fock method reported in this work, as well as a study of the plasma conditions.
Martins, M. C., J. P. Santos, A. M. Costa, and F. Parente. "Transition wavelengths and probabilities for spectral lines of Zr III." The European Physical Journal D 39 (2006): 167-172. AbstractWebsite

Wavelengths and oscillator strengths for all dipole-allowed fine-structure transitions in Zr III have been calculated within the Multi-Configuration Dirac-Fock method with QED corrections. These transitions are included in the spectrum of some chemically peculiar stars, like the B-type star Lupi observed by the Hubble space telescope. The results are compared to existing experimental and semi-empirical data. Corr

Martins, M. C., A. M. Costa, J. P. Santos, F. Parente, and P. Indelicato. "Relativistic calculation of two-electron one-photon and hypersatellite transition energies for 12<=Z<=30 elements." Journal of Physics B: Atomic and Molecular Physics 37 (2004): 3785-3795. AbstractWebsite

Energies of two-electron one-photon transitions from initial double K-hole states were computed using the Dirac–Fock model. The transition energies of competing processes, the Ka hypersatellites, were also computed. The results are compared with experiment and to other theoretical calculations.

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.

Martins, M. C., J. P. Marques, A. M. Costa, J. P. Santos, F. Parente, S. Schlesser, E. O. Le Bigot, and P. Indelicato. "Production and decay of sulfur excited species in an electron-cyclotron-resonance ion-source plasma." Physical Review A 80 (2009): 032501. AbstractWebsite

The most important processes for the creation of S12+ to S14+ ions excited states from the ground configurations of S9+ to S14+ ions in an electron cyclotron resonance ion source, leading to the emission of K x-ray lines, are studied. Theoretical values for inner-shell excitation and ionization cross sections, including double-KL and triple-KLL ionizations, transition probabilities and energies for the de-excitation processes, are calculated in the framework of the multiconfiguration Dirac-Fock method. With reasonable assumptions about the electron energy distribution, a theoretical Kalpha x-ray spectrum is obtained, which is compared to recent experimental data.

Martins, M. C., J. P. Santos, A. M. Costa, and F. Parente. "Transition wavelengths and probabilities for spectral lines of Zr III." The European Physical Journal D 39 (2006): 167-172. AbstractWebsite
Wavelengths and oscillator strengths for all dipole-allowed fine-structure transitions in Zr III have been calculated within the Multi-Configuration Dirac-Fock method with QED corrections. These transitions are included in the spectrum of some chemically peculiar stars, like the B-type star Lupi observed by the Hubble space telescope. The results are compared to existing experimental and semi-empirical data.
Martins, M. C., J. P. Marques, A. M. Costa, J. P. Santos, F. Parente, S. Schlesser, Le E. - O. Bigot, and P. Indelicato. "Production and decay of sulfur excited species in an electron-cyclotron-resonance ion-source plasma." Physical Review A (Atomic, Molecular, and Optical Physics) 80 (2009): 032501. AbstractWebsite
The most important processes for the creation of S12+ to S14+ ions excited states from the ground configurations of S9+ to S14+ ions in an electron cyclotron resonance ion source, leading to the emission of K x-ray lines, are studied. Theoretical values for inner-shell excitation and ionization cross sections, including double-KL and triple-KLL ionizations, transition probabilities and energies for the de-excitation processes, are calculated in the framework of the multiconfiguration Dirac-Fock method. With reasonable assumptions about the electron energy distribution, a theoretical Kalpha x-ray spectrum is obtained, which is compared to recent experimental data.
Marques, J., F. Parente, A. Costa, M. Martins, P. Indelicato, and J. P. Santos. "Decay of the 1s^{2}2s3p ^{3}P_{0} level in Be-like ions." Phys. Rev. A 86 (2012): 052521. AbstractWebsite

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Marques, J. P., P. Indelicato, F. Parente, J. M. Sampaio, and J. P. Santos. "Ground-state Landé <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>g</mi></math></span> factors for selected ions along the boron isoelectronic sequence." Physical Review A 94 (2016): 042504. AbstractWebsite

Land\'e $g$ factors for the fine-structure $1{s}^{2}2{s}^{2}2p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2}$ and $^{2}P_{3/2}$ levels in the boron isoelectronic sequence for selected $Z$ values have been calculated using the multiconfiguration Dirac-Fock method with both quantum-electrodynamic and electronic correlation corrections included. All-order Breit and vacuum polarization corrections were included in the calculation, with a fully optimized active set wave function. The results are compared with the available theoretical data, showing a very good agreement.

Marques, J. P., M. Guerra, F. Parente, J. P. Santos, P. Indelicato, and J. M. Sampaio. "K-shell width, fluorescence yield, and Kβ/ Kαintensity ratio calculation for Fe in the Dirac-Fock approach." Journal of Physics: Conference Series 635 (2015): 092094-2. AbstractWebsite
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Marques, J. P., M. C. Martins, A. M. Costa, P. Indelicato, F. Parente, and J. P. Santos. "Theoretical determination of K X-ray transition energy and probability values for highly charged (He- through B-like) Nd, Sm, Gd, Dy, Er, and Yb ions." Radiat. Phys. Chem. 154 (2019): 17-20. Abstract

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Marques, J. P., P. Indelicato, F. Parente, J. M. Sampaio, and J. P. Santos. "Ground-state Landé g factors for selected ions along the boron isoelectronic sequence." Physical Review A 94 (2016): 042504. AbstractWebsite

Land\'e $g$ factors for the fine-structure $1{s}^{2}2{s}^{2}2p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2}$ and $^{2}P_{3/2}$ levels in the boron isoelectronic sequence for selected $Z$ values have been calculated using the multiconfiguration Dirac-Fock method with both quantum-electrodynamic and electronic correlation corrections included. All-order Breit and vacuum polarization corrections were included in the calculation, with a fully optimized active set wave function. The results are compared with the available theoretical data, showing a very good agreement.

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

Madeira, T. I., J. M. Sampaio, M. Guerra, F. Parente, P. Indelicato, J. P. Santos, and J. P. Marques. "Relativistic calculation of K-, L- and M-shell x-ray fluorescence yields for Ba." Physica Scripta 90 (2015): 1-3. AbstractWebsite

Physica Scripta, 90(2015) 054009. doi:10.1088/0031-8949/90/5/054009

Machado, Jorge, {Patrícia M. S. } Carvalho, Ana Félix, Delfin Doutel, {José Paulo} Santos, {Maria Luísa} Carvalho, and Sofia Pessanha. "Accuracy improvement in XRF analysis for the quantification of elements ranging from tenths to thousands μg g-1in human tissues using different matrix reference materials." Journal of Analytical Atomic Spectrometry 35 (2020): 2920-2927. Abstract

In this work, we aim at achieving the most accurate quantitative determination of elements in human tissues by means of X-ray Fluorescence spectrometry using the external calibration approach. A calibration curve built using a set of certified reference materials (CRM) of animal tissue was compared with the one obtained with a set of CRMs of plants and leaves with lower atomic number Z but with correction of the matrix using the scattering peaks of the X-ray tube anode. Finally, a calibration curve combining the two sets of CRMs was built and the accuracy of the quantification using the three methods was compared and a more precise method of quantification was obtained. This improved approach was tested on five paired samples of normal and tumour human tissue. Despite the high heterogeneity of the samples, and given the improvement in accuracy of the measurements, significant differences were found in the elemental concentration of low-Z elements. This journal is

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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