José Paulo Santos

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.

Talanta, 155 + (2016) 107-115. doi:10.1016/j.talanta.2016.04.028

The use of a vacuum double crystal spectrometer, coupled to an electron-cyclotron resonance ion source (ECRIS), allows to measure low-energy x-ray transitions energies in highly-charged ions with accuracies of the order of a few parts per million. We have used this installation to measure the 1s2p 1 P1 - 1s2 1 S0 diagram line and the 1s2s 3 S1 - 1s2 1 S0 forbidden M1 transition energies in helium-like argon, the 1s2s2p 2 P j 1s2 2s 2 S1/2 transitions in lithium-like argon and the 1s2s2 2p 1 P1 - 1s2 2s2 1 S0 transition in beryllium-like argon. These transition measurements have accuracies between 2 and 4 ppm depending on the line intensity. Thanks to the excellent agreement between the simulations and the measurements, we were also able to measure the transition width of all the allowed transitions. The results are compared to recent QED and relativistic many-body calculations.

The use of a vacuum double crystal spectrometer, coupled to an electron-cyclotron resonance ion source (ECRIS), allows to measure low-energy x-ray transitions energies in highly-charged ions with accuracies of the order of a few parts per million. We have used this installation to measure the 1s2p 1 P1 - 1s2 1 S0 diagram line and the 1s2s 3 S1 - 1s2 1 S0 forbidden M1 transition energies in helium-like argon, the 1s2s2p 2 P j 1s2 2s 2 S1/2 transitions in lithium-like argon and the 1s2s2 2p 1 P1 - 1s2 2s2 1 S0 transition in beryllium-like argon. These transition measurements have accuracies between 2 and 4 ppm depending on the line intensity. Thanks to the excellent agreement between the simulations and the measurements, we were also able to measure the transition width of all the allowed transitions. The results are compared to recent QED and relativistic many-body calculations.

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

Journal of Quantitative Spectroscopy and Radiative Transfer, 182 + (2016) 87-93. doi:10.1016/j.jqsrt.2016.05.012

Atomic Data and Nuclear Data Tables, 117-118 (2017) 439-457. doi:10.1016/j.adt.2017.01.001

The two-photon $1{s}^{2}2s2p\phantom{\rule{0.16em}{0ex}}{}^{3}{P}_{0}\ensuremath{\rightarrow}1{s}^{2}{s}^{2}\phantom{\rule{0.16em}{0ex}}{}^{1}{S}_{0}$ transition in berylliumlike ions is investigated theoretically within a fully relativistic framework and a second-order perturbation theory. We focus our analysis on how electron correlation, as well as the negative-energy spectrum, can affect the forbidden $E1M1$ decay rate. For this purpose, we include the electronic correlation via an effective local potential and within a single-configuration-state model. Due to its experimental interest, evaluations of decay rates are performed for berylliumlike xenon and uranium. We find that the negative-energy contribution can be neglected at the present level of accuracy in the evaluation of the decay rate. On the other hand, if contributions of electronic correlation are not carefully taken into account, it may change the lifetime of the metastable state by up to 20%. By performing a fully relativistic $jj$-coupling calculation, we find a decrease of the decay rate by two orders of magnitude compared to nonrelativistic $LS$-coupling calculations, for the selected heavy ions.

Journal of Physics B: Atomic, Molecular and Optical Physics, 48(2015) 185202. doi:10.1088/0953-4075/48/18/185202

Journal of Quantitative Spectroscopy and Radiative Transfer, 174 + (2016) 79-87. doi:10.1016/j.jqsrt.2016.01.026

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The accumulation of lead in several bones of Wistar rats with time was determined and comparedQ3 for the different types of bones. Two groups were studied: a control group (n = 20), not exposedto lead and a contaminated group (n = 30), exposed to lead from birth, first indirectly throughmother’s milk, and then directly through a diet containing lead acetate in drinking water (0.2%).Rats age ranged from 1 to 11 months, with approximately 1 month intervals and each of thecollections had 3 contaminated rats and 2 control rats. Iliac, femur, tibia–fibula and skull havebeen analysed by energy dispersive X-ray fluorescence technique (EDXRF). Samples offormaldehyde used to preserve the bone tissues were also analysed by Electrothermal AtomicAbsorption (ETAAS), showing that there was no significant loss of lead from the tissue to thepreservative. The bones mean lead concentration of exposed rats range from 100 to 300 mg g 1while control rats never exceeded 10 mg g 1. Mean bone lead concentrations were compared andthe concentrations were higher in iliac, femur and tibia–fibula and after that skull. However, ofall the concentrations in the different collections, only those in the skull were statisticallyQ4 significantly different (p o 0.05) from the other types of bones. Analysis of a radar chart alsoallowed us to say that these differences tend to diminish with age. The Spearman correlation testapplied to mean lead concentrations showed strong and very strong positive correlations betweenall different types of bones. This test also showed that mean lead concentrations in bones arenegatively correlated with the age of the animals. This correlation is strong in iliac and femur andvery strong in tibia–fibula and skull. It was also shown that the decrease of lead accumulationwith age is made by three plateaus of accumulation,

The accumulation of lead in several bones of Wistar rats with time was determined and compared Q3 for the different types of bones. Two groups were studied: a control group (n = 20), not exposed to lead and a contaminated group (n = 30), exposed to lead from birth, first indirectly through
mother’s milk, and then directly through a diet containing lead acetate in drinking water (0.2%). Rats age ranged from 1 to 11 months, with approximately 1 month intervals and each of the collections had 3 contaminated rats and 2 control rats. Iliac, femur, tibia–fibula and skull have been analysed by energy dispersive X-ray fluorescence technique (EDXRF). Samples of formaldehyde used to preserve the bone tissues were also analysed by Electrothermal Atomic Absorption (ETAAS), showing that there was no significant loss of lead from the tissue to the preservative. The bones mean lead concentration of exposed rats range from 100 to 300 mg g 1 while control rats never exceeded 10 mg g 1. Mean bone lead concentrations were compared and
the concentrations were higher in iliac, femur and tibia–fibula and after that skull. However, of all the concentrations in the different collections, only those in the skull were statistically Q4 significantly different (p o 0.05) from the other types of bones. Analysis of a radar chart also allowed us to say that these differences tend to diminish with age. The Spearman correlation test applied to mean lead concentrations showed strong and very strong positive correlations between
all different types of bones. This test also showed that mean lead concentrations in bones are negatively correlated with the age of the animals. This correlation is strong in iliac and femur and very strong in tibia–fibula and skull. It was also shown that the decrease of lead accumulation with age is made by three plateaus of accumulation,

The accumulation of lead in several bones of Wistar rats with time was determined and compared Q3 for the different types of bones. Two groups were studied: a control group (n = 20), not exposed to lead and a contaminated group (n = 30), exposed to lead from birth, first indirectly throughmother’s milk, and then directly through a diet containing lead acetate in drinking water (0.2%). Rats age ranged from 1 to 11 months, with approximately 1 month intervals and each of the collections had 3 contaminated rats and 2 control rats. Iliac, femur, tibia–fibula and skull have been analysed by energy dispersive X-ray fluorescence technique (EDXRF). Samples of formaldehyde used to preserve the bone tissues were also analysed by Electrothermal Atomic Absorption (ETAAS), showing that there was no significant loss of lead from the tissue to the preservative. The bones mean lead concentration of exposed rats range from 100 to 300 mg g 1 while control rats never exceeded 10 mg g 1. Mean bone lead concentrations were compared andthe concentrations were higher in iliac, femur and tibia–fibula and after that skull. However, of all the concentrations in the different collections, only those in the skull were statistically Q4 significantly different (p o 0.05) from the other types of bones. Analysis of a radar chart also allowed us to say that these differences tend to diminish with age. The Spearman correlation test applied to mean lead concentrations showed strong and very strong positive correlations betweenall different types of bones. This test also showed that mean lead concentrations in bones are negatively correlated with the age of the animals. This correlation is strong in iliac and femur and very strong in tibia–fibula and skull. It was also shown that the decrease of lead accumulation with age is made by three plateaus of accumulation,

The C 1s and N 1s photoelectron spectra of gas-phase 5-aminotetrazole (5ATZ) were recorded using synchrotron radiation, with the aim of evaluating 1H/2H tautomer population ratios. The core-electron binding energies (CEBEs) were estimated from computational results, using the delta self-consistent-field (ΔSCF) approach. Simulated spectra were generated using these CEBEs and the results from Gaussian-n (Gn, n=1, 2 and 3) and Complete Basis Set (CBS-4M and CBS-Q) methods. Results reveal the almost exclusive predominance of the 2H-tautomer, with a 1H/2H ratio of ca. 0.12/0.88, taken from a gross analysis of the XPS C 1s spectrum, recorded at 365 K.

The C 1s and N 1s photoelectron spectra of gas-phase 5-aminotetrazole (5ATZ) were recorded using synchrotron radiation, with the aim of evaluating 1H/2H tautomer population ratios. The core-electron binding energies (CEBEs) were estimated from computational results, using the delta self-consistent-field (ΔSCF) approach. Simulated spectra were generated using these CEBEs and the results from Gaussian-n (Gn, n=1, 2 and 3) and Complete Basis Set (CBS-4M and CBS-Q) methods. Results reveal the almost exclusive predominance of the 2H-tautomer, with a 1H/2H ratio of ca. 0.12/0.88, taken from a gross analysis of the XPS C 1s spectrum, recorded at 365 K.

The relative populations of the 1H- and 2H-tautomer of gas-phase 5-methyltetrazole (5MTZ) have been assessed through core-level photoelectron spectroscopy, and compared with the results obtained from Gaussian-n (Gn, n = 1, 2 and 3) and Complete Basis Set methods (CBS-4M and CBS-Q). The C 1s and N 1s core‚Äìelectron binding energies (CEBEs) for each ionization site of both tautomers have been computed using the Œîself-consistent-field (ŒîSCF) approach. The C 1s and N 1s XPS spectra, obtained at 313 K, yield a 1H/2H tautomer ratio of ca. 0.16/0.84 and 0.21/0.79, respectively.

Chemical Physics Letters, 516 (2011) 149-153. doi:10.1016/j.cplett.2011.10.001