Recent Publications

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2013
Guerra, M., R. M. Pinto, J. P. Santos, and A. C. S. Paiva. "Towards the assignment of the REMPI spectrum of Ph 2O using CIS and TD-DFT methods." Molecular Physics 111 (2013): 3311-3319. AbstractWebsite
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EPS. "Euphysics News." 44 (2013): 1-36. Abstract
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Pé-Leve Santos, Sara C., Mariana Eloy Cruz, António M. E. Barroso, Catarina P. S. Fonseca, Mauro Guerra, Maria Luisa Carvalho, and Jose Paulo Santos. "Elemental characterization of plants and soils in Panasqueira tungsten mining region." Online (2013). AbstractWebsite
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Amaro, P., S. Schlesser, M. Guerra, E. Le Bigot, J. P. Santos, C. I. Szabo, A. Gumberidze, and P. Indelicato. "Absolute measurements and simulations of x-ray line energies of highly charged ions with a double-crystal spectrometer." T156 (2013): 014104. AbstractWebsite
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Amaro, P., S. Schlesser, M. Guerra, E. Le Bigot, J. P. Santos, C. I. Szabo, A. Gumberidze, and P. Indelicato. "Absolute measurements and simulations of x-ray line energies of highly charged ions with a double-crystal spectrometer." Physica Scripta T156 (2013): 014104. AbstractWebsite
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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
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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
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Santos, J. P., J. P. Marques, A. M. Costa, M. C. Martins, P. Indelicato, and F. Parente. "Transition probability values of the 1s 22s3p 3P 0level in Be-like ions." Physica Scripta T156 (2013): 014020. AbstractWebsite
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Santos, J. P., J. P. Marques, A. M. Costa, M. C. Martins, P. Indelicato, and F. Parente. "Transition probability values of the 1s 22s3p 3P 0level in Be-like ions." Physica Scripta T156 (2013): 014020. AbstractWebsite
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2014
Sampaio, J. M., T. I. Madeira, J. P. Marques, F. Parente, A. M. Costa, P. Indelicato, J. P. Santos, M. - C. Lépy, and Y. Ménesguen. "Approaches for theoretical and experimental determinations of K-shell decay rates and fluorescence yields in Ge." Physical Review A 89 (2014): 012512. AbstractWebsite
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Sampaio, J. M., T. I. Madeira, J. P. Marques, F. Parente, A. M. Costa, P. Indelicato, J. P. Santos, M. - C. Lépy, and Y. Ménesguen. "Approaches for theoretical and experimental determinations of K-shell decay rates and fluorescence yields in Ge." Physical Review A 89 (2014): 012512. AbstractWebsite
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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, 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 ...

Tendeiro, Diogo, Gonçalo Lopes, Pedro Vieira, and Jose Paulo Santos. "Monte Carlo simulation of laser beams interaction with the human eye using Geant4." BioMedical Engineering OnLine 13 (2014): 58. AbstractWebsite
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Tendeiro, Diogo, Gonçalo Lopes, Pedro Vieira, and Jose Paulo Santos. "Monte Carlo simulation of laser beams interaction with the human eye using Geant4." BioMedical Engineering OnLine 13 (2014): 58. AbstractWebsite
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Lopes, G., D. Tendeiro, J. P. Santos, and P. Vieira. "Monte Carlo Simulation of Radiation through the Human Retina Using Geant4.", 431-434. Vol. 41. Cham: Springer International Publishing, 2014. Abstract
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Lopes, G., D. Tendeiro, J. P. Santos, and P. Vieira. "Monte Carlo Simulation of Radiation through the Human Retina Using Geant4.", 431-434. Vol. 41. Cham: Springer International Publishing, 2014. Abstract
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Sampaio, J. M., T. I. Madeira, F. Parente, P. Indelicato, J. P. Santos, and J. P. Marques. "Relativistic calculations of M-shell photoionization and X-ray production cross-sections for Hg at 5.96 keV excitation energy." Radiation Physics and Chemistry 107 (2014): 36. AbstractWebsite

In this work we calculate photoionization and X-ray production cross-sections (XPCS) of M-shell vacancies in Hg at incident photon energy of 5.96 keV (low.

Kasthurirangan, S., J. K. Saha, A. N. Agnihotri, A. Banerjee, A. Kumar, D. Misra, J. P. Santos, A. M. Costa, P. Indelicato, T. K. Mukherjee, and L. C. Tribedi. "High-resolution x-ray spectra from highly charged Si, S and Cl ions showing evidence of fluorescence active resonant states." Journal of Physics: Conference Series 488 (2014): 132027-2. AbstractWebsite

We have measured the x-ray spectra from highly charged Si, S and Cl ions in collisions with thin foils using a high-resolution x-ray spectrometer. The observed lines have been assigned to various transitions in H-, He- and Li-like ions. For proper identification of line positions, the theoretical calculations have been carried out using a state-of-the-art MCDF code including QED effects, with which the experimental data is in excellent agreement. We have also observed, for the first time, x-rays arising out of the decay of long-lived resonant states in the He-like ions of each species. Details will be presented.

Santos, I., M. S. Diniz, M. L. Carvalho, and J. P. Santos. "Assessment of Essential Elements and Heavy Metals Content on Mytilus galloprovincialis from River Tagus Estuary." Biological Trace Element Research (2014). AbstractWebsite

Trace elemental content was analysed in edible tissues of Mytilus galloprovincialis collected in five different sampling areas near the mouth of river Tagus estuary in Lisbon. The concentrations of essential elements (S, K, Ca, Fe, Cu, Zn, As, Br and Sr) were determined by energy-dispersive X-ray fluorescence (EDXRF) spectrometry, while toxic elements (Cr, Cd, Hg, Se and Pb) were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results show that the essential elements K and S are present at the highest concentrations in all the studied samples reaching 2,920 and 4,520 μg g(-1) (fresh weight), respectively. The highest levels of heavy metals found were in two areas close to the city for Pb and Cd, but below the maximum allowed values.

Fratini, F., L. Safari, A. G. Hayrapetyan, K. Jankala, P. Amaro, and J. P. Santos. "Quantized form factor shift in the presence of free electron laser radiation." EPL (Europhysics Letters) 107 (2014): 13002. AbstractWebsite

In electron scattering, the target form factors contribute significantly to the diffraction pattern and carry information on the target electromagnetic charge distribution. Here we show that the presence of electromagnetic radiation, as intense as currently available in free electron lasers, shifts the dependence of the target form factors by a quantity that depends on the number of photons absorbed or emitted by the electron as well as on the parameters of the electromagnetic radiation. As example, we show the impact of intense ultraviolet and soft X-ray radiation on elastic electron scattering by the Ne-like argon ion and by the xenon atom. We find that the shift brought by the radiation to the form factor is of the order of some percent. Our results may open up a new avenue to explore matter with the assistance of laser.

Fratini, F., L. Safari, A. G. Hayrapetyan, K. Jankala, P. Amaro, and J. P. Santos. "Quantized form factor shift in the presence of free electron laser radiation." EPL (Europhysics Letters) 107 (2014): 13002. AbstractWebsite

In electron scattering, the target form factors contribute significantly to the diffraction pattern and carry information on the target electromagnetic charge distribution. Here we show that the presence of electromagnetic radiation, as intense as currently available in free electron lasers, shifts the dependence of the target form factors by a quantity that depends on the number of photons absorbed or emitted by the electron as well as on the parameters of the electromagnetic radiation. As example, we show the impact of intense ultraviolet and soft X-ray radiation on elastic electron scattering by the Ne-like argon ion and by the xenon atom. We find that the shift brought by the radiation to the form factor is of the order of some percent. Our results may open up a new avenue to explore matter with the assistance of laser.

Safari, L., P. Amaro, J. P. Santos, and F. Fratini. "Angular and polarization analysis for two-photon decay of <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>2</mn><mi>s</mi></mrow></math>&." Physical Review A 90 (2014): 014502. AbstractWebsite

The amplitude of two-photon transitions between hyperfine states in hydrogenlike ions is derived based on the relativistic Dirac equation and second-order perturbation theory. We study angular and linear polarization properties of the photon pair emitted in the decay of $2s$ states, where spin-flip and non-spin-flip transitions are highlighted. We pay particular attention to hydrogenlike uranium, since it is an ideal candidate for investigating relativistic and high-multipole effects, such as spin-flip transitions. Two types of emission patterns are identified: (i) non-spin-flip transitions are found to be characterized by an angular distribution of the type $W($\theta${})$\sim${}1+{cos}^{2}$\theta${}$ while the polarizations of the emitted photons are parallel; and (ii) spin-flip transitions have somewhat smaller decay rates and are found to be characterized by an angular distribution of the type $W($\theta${})$\sim${}1$-${}1/3{cos}^{2}$\theta${}$ while the polarizations of the emitted photons are orthogonal, where $$\theta${}$ is the angle between photons directions. Deviations due to nondipole and relativistic contributions are evaluated for both types of transitions. This work is the first step toward exploring the effect of the nucleus over the angular and polarization properties of the photon pairs emitted by two-photon transitions.

Safari, L., P. Amaro, J. P. Santos, and F. Fratini. "Angular and polarization analysis for two-photon decay of <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>2</mn><mi>s</mi></mrow></math>&." Physical Review A 90 (2014): 014502. AbstractWebsite

The amplitude of two-photon transitions between hyperfine states in hydrogenlike ions is derived based on the relativistic Dirac equation and second-order perturbation theory. We study angular and linear polarization properties of the photon pair emitted in the decay of $2s$ states, where spin-flip and non-spin-flip transitions are highlighted. We pay particular attention to hydrogenlike uranium, since it is an ideal candidate for investigating relativistic and high-multipole effects, such as spin-flip transitions. Two types of emission patterns are identified: (i) non-spin-flip transitions are found to be characterized by an angular distribution of the type $W($\theta${})$\sim${}1+{cos}^{2}$\theta${}$ while the polarizations of the emitted photons are parallel; and (ii) spin-flip transitions have somewhat smaller decay rates and are found to be characterized by an angular distribution of the type $W($\theta${})$\sim${}1$-${}1/3{cos}^{2}$\theta${}$ while the polarizations of the emitted photons are orthogonal, where $$\theta${}$ is the angle between photons directions. Deviations due to nondipole and relativistic contributions are evaluated for both types of transitions. This work is the first step toward exploring the effect of the nucleus over the angular and polarization properties of the photon pairs emitted by two-photon transitions.