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F
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.

E
EPS. "Euphysics News." 44 (2013): 1-36. Abstract
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Ensina, Ana, Patr{\'ı}cia M. Carvalho, Jorge Machado, Maria Lu{\'ı}sa Carvalho, Diogo Casal, Diogo Pais, José Paulo Santos, António A. Dias, and Sofia Pessanha. "Analysis of human tissues using Energy Dispersive X Ray Fluorescence – Dark matrix determination for the application to cancer research." Journal of Trace Elements in Medicine and Biology 68 (2021): 126837. AbstractWebsite
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D
Dyke, J. M., G. Levita, A. Morris, J. S. Ogden, A. A. Dias, M. Algarra, J. P. Santos, M. L. Costa, P. Rodrigues, M. M. Andrade, and M. T. Barros. "Contrasting Behavior in Azide Pyrolyses: An Investigation of the Thermal Decompositions of Methyl Azidoformate, Ethyl Azidoformate and 2-Azido-N, N-dimethylacetamide by Ultraviolet Photoelectron Spectroscopy and Matrix Isolation Infrared Spectroscopy." Chemistry - A European Journal 11 (2005): 1665-1676. Abstract
The thermal decompositions of methyl azidoformate (N3COOMe), ethyl azidoformate (N3COOEt) and 2-azido-N,N-dimethylacetamide (N3CH2CONMe2) have been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. N2 appears as an initial pyrolysis product in all systems, and the principal interest lies in the fate of the accompanying organic fragment. For methyl azidoformate, four accompanying products were observed: HNCO, H2CO, CH2NH and CO2, and these are believed to arise as a result of two competing decomposition routes of a four-membered cyclic intermediate. Ethyl azidoformate pyrolysis yields four corresponding products: HNCO, MeCHO, MeCHNH and CO2, together with the five-membered-ring compound 2-oxazolidone. In contrast, the initial pyrolysis of 2-azido-N,N-dimethyl acetamide, yields the novel imine intermediate Me2NCOCHNH, which subsequently decomposes into dimethyl formamide (HCONMe2), CO, Me2NH and HCN. This intermediate was detected by matrix isolation IR spectroscopy, and its identity confirmed both by a molecular orbital calculation of its IR spectrum, and by the temperature dependence and distribution of products in the PES and IR studies. Mechanisms are proposed for the formation and decomposition of all the products observed in these three systems, based on the experimental evidence and the results of supporting molecular orbital calculations.
Dyke, J. M., G. Levita, A. Morris, J. S. Ogden, A. A. Dias, M. Algarra, J. P. Santos, M. L. Costa, P. Rodrigues, M. M. Andrade, and M. T. Barros. "Contrasting Behavior in Azide Pyrolyses: An Investigation of the Thermal Decompositions of Methyl Azidoformate, Ethyl Azidoformate and 2-Azido-N, N-dimethylacetamide by Ultraviolet Photoelectron Spectroscopy and Matrix Isolation Infrared Spectroscopy." Chemistry - A European Journal 11 (2005): 1665-1676. Abstract

The thermal decompositions of methyl azidoformate (N3COOMe), ethyl azidoformate (N3COOEt) and 2-azido-N,N-dimethylacetamide (N3CH2CONMe2) have been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. N2 appears as an initial pyrolysis product in all systems, and the principal interest lies in the fate of the accompanying organic fragment. For methyl azidoformate, four accompanying products were observed: HNCO, H2CO, CH2NH and CO2, and these are believed to arise as a result of two competing decomposition routes of a four-membered cyclic intermediate. Ethyl azidoformate pyrolysis yields four corresponding products: HNCO, MeCHO, MeCHNH and CO2, together with the five-membered-ring compound 2-oxazolidone. In contrast, the initial pyrolysis of 2-azido-N,N-dimethyl acetamide, yields the novel imine intermediate Me2NCOCHNH, which subsequently decomposes into dimethyl formamide (HCONMe2), CO, Me2NH and HCN. This intermediate was detected by matrix isolation IR spectroscopy, and its identity confirmed both by a molecular orbital calculation of its IR spectrum, and by the temperature dependence and distribution of products in the PES and IR studies. Mechanisms are proposed for the formation and decomposition of all the products observed in these three systems, based on the experimental evidence and the results of supporting molecular orbital calculations.

Dyke, J. M., G. Levita, A. Morris, J. S. Ogden, A. A. Dias, M. Algarra, J. P. Santos, M. L. Costa, P. Rodrigues, and M. T. Barros. "A Study of the Thermal Decomposition of 2-Azidoacetamide by Ultraviolet Photoelectron Spectroscopy and Matrix-Isolation Infrared Spectroscopy:  Identification of the Imine Intermediate H2NCOCHNH." The Journal of Physical Chemistry A 108 (2004): 5299-5307. AbstractWebsite

The thermal decomposition of 2-azidoacetamide (N3CH2CONH2) has been studied by matrix-isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. N2, CH2NH, HNCO, CO, NH3, and HCN are observed as high-temperature decomposition products, while at lower temperatures, the novel imine intermediate H2NCOCHNH is observed in the matrix-isolation IR experiments. The identity of this intermediate is confirmed both by ab initio molecular orbital calculations of its IR spectrum and by the temperature dependence and distribution of products in the photoelectron spectroscopy (PES) and IR studies. Mechanisms are proposed for the formation and decomposition of the intermediate consistent both with the observed results and with estimated activation energies based on pathway calculations.

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
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Costa, A. M., M. C. Martins, J. P. Santos, P. Indelicato, and F. Parente. "Relativistic calculation of Kβ hypersatellite energies and transition probabilities for selected atoms with 13<=Z<=80." Journal of Physics B: Atomic and Molecular Physics 39 (2006): 2355-2366. AbstractWebsite
Energies and transition probabilities of Kβ hypersatellite lines are computed using the Dirac–Fock model for several values of Z throughout the periodic table. The influence of the Breit interaction on the energy shifts from the corresponding diagram lines and on the Kβh1/Kβh3 intensity ratio is evaluated. The widths of the double-K hole levels are calculated for Al and Sc. The results are compared to experiment and to other theoretical calculations.
Costa, A. M., M. C. Martins, J. P. Santos, P. Indelicato, and F. Parente. "Relativistic calculation of Kα hypersatellite line energies and transition probabilities for selected atoms with 12<=Z<=80." Journal of Physics B: Atomic, Molecular and Optical Physics 40 (2007): 57. AbstractWebsite
The transition probabilities of Kα hypersatellite lines and energy shifts with respect to the corresponding diagram lines are computed using the Dirac–Fock model for several values of atomic number Z throughout the periodic table. The influence of the Breit interaction on the Kα1h/Kα2h line intensity ratio, Kα1h and Kα2h line energy shifts and Kα1h to Kα2h line energy splitting is evaluated. Double-K shell hole threshold values for selected elements with 23 ⩽Z⩽ 30, calculated within the same approach, are compared with available experimental results.
Costa, A. M., M. C. Martins, J. P. Santos, P. Indelicato, and F. Parente. "Relativistic calculation of Kβ hypersatellite energies and transition probabilities for selected atoms with 13 ≤ Z ≤ 80." Journal of Physics B: Atomic and Molecular Physics 39 (2006): 2355-2366. AbstractWebsite

Energies and transition probabilities of Kβ hypersatellite lines are computed using the Dirac–Fock model for several values of Z throughout the periodic table. The influence of the Breit interaction on the energy shifts from the corresponding diagram lines and on the Kβh1/Kβh3 intensity ratio is evaluated. The widths of the double-K hole levels are calculated for Al and Sc. The results are compared to experiment and to other theoretical calculations.Al_Sc_Mg_Ti

Costa, A. M., M. C. Martins, J. P. Santos, P. Indelicato, and F. Parente. "Relativistic calculation of K&alpha; hypersatellite line energies and transition probabilities for selected atoms with 12 ≤ Z ≤ 80." Journal of Physics B: Atomic, Molecular and Optical Physics 40 (2007): 57. AbstractWebsite

The transition probabilities of K&alpha; hypersatellite lines and energy shifts with respect to the corresponding diagram lines are computed using the Dirac&ndash;Fock model for several values of atomic number <I>Z</I> throughout the periodic table. The influence of the Breit interaction on the K&alpha;<SUB>1</SUB><SUP>h</SUP>/K&alpha;<SUB>2</SUB><SUP>h</SUP> line intensity ratio, K&alpha;<SUB>1</SUB><SUP>h</SUP> and K&alpha;<SUB>2</SUB><SUP>h</SUP> line energy shifts and K&alpha;<SUB>1</SUB><SUP>h</SUP> to K&alpha;<SUB>2</SUB><SUP>h</SUP> line energy splitting is evaluated. Double-K shell hole threshold values for selected elements with 23 &les;<I>Z</I>&les; 30, calculated within the same approach, are compared with available experimental results.

Costa, A. M., M. C. Martins, J. P. Santos, P. Indelicato, and F. Parente. "Dirac-Fock Transition Energies and Radiative and Radiationless Transition Probabilities for Ar8+ to Ar16+ Ion Levels with K-Shell Hole." Atomic Data and Nuclear Data Tables 79 (2001): 223-239. Abstract
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Carvalho, Patr{\'ı}cia M. S., Sofia Pessanha, Jorge Machado, Ana Lu{\'ı}sa Silva, João Veloso, Diogo Casal, Diogo Pais, and José Paulo Santos. "Energy dispersive X-ray fluorescence quantitative analysis of biological samples with the external standard method." Spectrochimica Acta Part B: Atomic Spectroscopy 174 (2020): 105991. AbstractWebsite
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da Carvalho, {Patrícia Miguel Silva}, Fábio Leite, {A. L. M. } Silva, Sofia Pessanha, {Maria Luísa} Carvalho, {João F. C. A. } Veloso, and {José Paulo} Santos. "Elemental mapping of Portuguese ceramic pieces with a full-field XRF scanner based on a 2D-THCOBRA detector." European Physical Journal Plus 136 (2021). Abstract

In this work, we present a novel application of the full-field energy-dispersive X-ray fluorescence (EDXRF) imaging system based on a MicroPattern Gaseous Detector (2D-THCOBRA) in the cultural heritage field. The detector has an intrinsic imaging capability with spatial resolution of 400μmFWHM, and is energy sensitive, presenting an energy resolution of approximately 1keVFWHM at 5.9keV. The full-field XRF scanner based on the 2D-THCOBRA detector allows mapping the distribution of elements in large area samples with high detection efficiency (75 % at 5.9keV), being a very promising choice for elemental mapping analysis of large area cultural heritage samples. In this work, we have demonstrated the imaging capabilities of the full-field XRF scanner and used it to assess the restoration of a Portuguese faience piece.

Cardoso, Pedro, Pedro Amaro, Jose Paulo Santos, Joaquim T. de Assis, and Maria Luisa Carvalho. "Determination of Nickel and Manganese Contaminants in Pharmaceutical Iron Supplements Using Energy Dispersive X-ray Fluorescence." Applied Spectroscopy 71 (2017): 432-437. AbstractWebsite
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Cardoso, Pedro, Pedro Amaro, Jose Paulo Santos, Joaquim T. de Assis, and Maria Luisa Carvalho. "Determination of Nickel and Manganese Contaminants in Pharmaceutical Iron Supplements using Energy Dispersive X-ray Fluorescence." Applied Spectroscopy (2016). AbstractWebsite

In this study, we investigate the capability of energy dispersive X-ray fluorescence (EDXF) spectrometry in a triaxial geometry apparatus as a fast and nondestructive determination method of both dominant and contaminant elements in pharmaceutical iron supplements. The following iron supplements brands with their respective active ingredients were analyzed: Neutrofer fólico (iron gylcinate), Anemifer (iron(II) sulfate monohydrate), Noripurum (iron(III)-hydroxide polymaltose complex), Sulferbel (iron(II) sulfate monohydrate), and Combiron Fólico (carbonyl iron). Although we observe a good agreement between the iron content obtained by the present method and that indicated in the supplement's prescribed dose, we observe contamination by manganese and nickel of up to 180 μg and 36 μg, respectively. These contents correspond to 7.2% and 14.4% of the permitted daily exposure of manganese and nickel, respectively, for an average adult individual as determined by the European Medicine Agency (EMEA). The method was successfully validated against the concentrations of several certified reference materials of biological light matrices with similar concentrations of contaminants. Moreover, we also validated our method by comparing the concentrations with those obtained with the inductively coupled plasma-atomic emission technique.

Cardoso, P., T. C. Mateus, G. Velu, R. P. Singh, J. P. Santos, M. L. Carvalho, V. M. Louren{\c c}o, F. Lidon, F. Reboredo, and M. Guerra. "Localization and distribution of Zn and Fe in grains of biofortified bread wheat lines through micro- and triaxial-X-ray fluorescence spectrometry." Spectrochim. Acta Part B 141 (2018): 70-79. Abstract

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Benis, E. P., S. Doukas, T. J. M. Zouros, P. Indelicato, F. Parente, C. Martins, J. P. Santos, and J. P. Marques. "Evaluation of the effective solid angle of a hemispherical deflector analyser with injection lens for metastable Auger projectile states." Nuclear Inst. and Methods in Physics Research, B 365 (2015): 457-461. AbstractWebsite

Nuclear Inst. and Methods in Physics Research, B, 365 (2015) 457-461. doi:10.1016/j.nimb.2015.07.006

A
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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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., J. P. Santos, F. Parente, A. Surzhykov, and P. Indelicato. "Resonance effects on the two-photon emission from hydrogenic ions." Physical Review A (Atomic, Molecular, and Optical Physics) 79 (2009): 062504. AbstractWebsite
A theoretical study of the all two-photon transitions from initial bound states with ni=2,3 in hydrogenic ions is presented. High-precision values of relativistic decay rates for ions with nuclear charge in the range 1<=Z<=92 are obtained through the use of finite basis sets for the Dirac equation constructed from B splines. We also report the spectral (energy) distributions of several resonant transitions, which exhibit interesting structures, such as zeros in the emission spectrum, indicating that two-photon emission is strongly suppressed at certain frequencies. We compare two different approaches (the line profile approach and the QED approach based on the analysis of the relativistic two-loop self-energy) to regularize the resonant contribution to the decay rate. Predictions for the pure two-photon contributions obtained in these approaches are found to be in good numerical agreement.
Amaro, P., F. Fratini, S. Fritzsche, P. Indelicato, J. P. Santos, and A. Surzhykov. "Parametrization of the angular correlation and degree of linear polarization in two-photon decays of hydrogenlike ions." Physical Review A 86 (2012): 042509. AbstractWebsite

The spontaneous two-photon emission in hydrogenlike ions is investigated within the framework of second- order perturbation theory and Dirac’s equation. Special attention is paid to the angular correlation of the emitted photons as well as to the degree of linear polarization of one of the two photons, if the second is just observed under arbitrary angles. Expressions for the angular correlation and the degree of linear polarization are expanded in powers of cosine functions of the two-photon opening angle, whose coefficients depend on the atomic number and the energy sharing of the emitted photons. The effects of including higher (electric and magnetic) multipoles upon the emitted photon pairs beyond the electric-dipole approximation are also discussed. Calculations of the coefficients are performed for the transitions 2s1/2 → 1s1/2, 3d3/2 → 1s1/2, and 3d5/2 → 1s1/2, along the entire hydrogen isoelectronic sequence (1 Z 100).