A5042429338- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Molecular Physics
- Electron and X-Ray Spectroscopy Techniques
- Advanced Chemical Physics Studies
- Nuclear physics research studies
- X-ray Diffraction in Crystallography
- Laser-induced spectroscopy and plasma
- Nuclear Physics and Applications
- Mass Spectrometry Techniques and Applications
- Radiation Shielding Materials Analysis
- Radioactive Decay and Measurement Techniques
- Advanced X-ray and CT Imaging
- Cold Atom Physics and Bose-Einstein Condensates
- Ion-surface interactions and analysis
- Advanced X-ray Imaging Techniques
- History and advancements in chemistry
- Molecular Junctions and Nanostructures
- Radioactive element chemistry and processing
- Scientific Measurement and Uncertainty Evaluation
- Crystallography and Radiation Phenomena
- Laser-Matter Interactions and Applications
- Inorganic Fluorides and Related Compounds
- Chemical Reactions and Mechanisms
- Quantum and Classical Electrodynamics
- Particle accelerators and beam dynamics
University of Lisbon
2006-2024
Universidade Nova de Lisboa
2015-2024
Centre National de la Recherche Scientifique
1993-2019
Laboratoire Kastler Brossel
2019
Sorbonne Université
1989-2019
Centro de Genética Clínica
2012
Departamento de Ciência e Tecnologia
2009
University of California, Berkeley
1989
Instituto de Investigação Científica Tropical
1981
University of Oregon
1980
Absolute energies of the $\mathrm{Ar}K$, $\mathrm{Kr}K$, and $\mathrm{Xe}{L}_{1}$, ${L}_{2}$, ${L}_{3}$ levels have been determined from absorption edges measured with synchrotron radiation. The double-crystal x-ray monochromator was calibrated by a method that ties energy scale directly to crystal lattice constant $\mathrm{hc}$. Theoretical model spectra were constructed \ensuremath{\ge} 4 Lorentzians representing lowest-energy one-electron electric-dipole transitions bound excited states,...
Formulas for the total ionization cross section by electron impact based on binary-encounter-dipole (BED) model and its simpler version, binary-encounter-Bethe (BEB) are extended to relativistic incident energies. Total sections hydrogen helium atoms from new formulas compared experimental data. Relativistic effects double of H He at energy $\ensuremath{\approx}300 \mathrm{keV}$ dominate thereafter. A simple modification original BED-BEB is proposed applications ion targets inner-shell...
The relativistic version of the binary-encounter Bethe (BEB) model is used to calculate cross sections for K-shell ionization atoms by electron impact. BEB requires only two atomic constants, binding energy and kinetic K electrons. These constants are listed carbon antimony. Comparisons with available experimental data on N, O, Na, Al, Cl, Ca, Cu, Se Sb show good agreement. C, Mg, P, S, Cr, As Cd tabulated.
The magnetic interaction has been shown to produce inversion of 1s2p $^{3}\mathrm{P}_{1}$ and $^{3}P_{0}$ for Z\ensuremath{\le}3 Z\ensuremath{\ge}46. In this paper we have used the multiconfiguration Dirac-Fock method compute with high precision 2 $^{3}\mathrm{P}_{1}$--2 separation energy, including relativistic contributions electron-electron correlations radiative corrections. This energy happens be very small around crossing, so that hyperfine can mix both levels significantly. We then...
Abstract The main objective of this study is to obtain three-dimensional empirical K-shell x-ray fluorescence cross-section ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>σ</mml:mi> </mml:mrow> <mml:mi>K</mml:mi> <mml:mi>α</mml:mi> </mml:msub> <mml:mo>,</mml:mo> <mml:mi>β</mml:mi> </mml:math> and <mml:mi mathvariant="italic">tot</mml:mi> <mml:mo stretchy="false">)</mml:mo> values for a wide range elements <mml:mfenced close=")"...
In this paper, we used the multiconfiguration Dirac-Fock method to compute with high precision 1${\mathit{s}}^{2}$2s2p $^{3}$${\mathit{P}}_{1}$--1${\mathit{s}}^{2}$2s2p $^{3}$${\mathit{P}}_{0}$ separation energy in berylliumlike ions, including relativistic contribution electron-electron correlations and radiative corrections. The effect of hyperfine interaction on both lifetimes those levels has been evaluated. absence nuclear magnetic moment level can decay ground state only by an E1-M1...
A new method is described which capable of determining \ensuremath{\Vert}\ensuremath{\Delta}${\mathrm{E}}_{0\mathrm{\ensuremath{-}}1}$\ensuremath{\Vert}, the absolute value fine-structure splitting interval ${2}^{3}$${\mathrm{P}}_{0}$-${2}^{3}$${\mathrm{P}}_{1}$ from hyperfine quenched lifetime ${2}^{3}$${\mathrm{P}}_{0}$ state heliumlike ions with nuclear spin. Based on this a measurement reported...
We have investigated systematically the $K\ensuremath{\alpha}$ x-ray spectra in elements from Ca to Ge within Berger's two-Lorentzian functions model, using a high-resolution antiparallel double-crystal spectrometer, order obtain detail physical meaning of asymmetry spectral profiles. The overall tendency corrected full width at half maximum $K{\ensuremath{\alpha}}_{1}$ and $K{\ensuremath{\alpha}}_{2}$ lines as function $Z$, well linewidths, are good agreement with data reported literature....
The $K\ensuremath{\beta}$ x-ray spectra of the elements from Ca to Ge have been systematically investigated using a high-resolution antiparallel double-crystal spectrometer. Each $K{\ensuremath{\beta}}_{1,3}$ natural linewidth has corrected instrumental function this type spectrometer, and spin doublet energies obtained peak position values in spectra. For all studied $K{\ensuremath{\beta}}_{1}$ lines FWHM increase linearly as $Z$. However, for $K{\ensuremath{\beta}}_{3}$ dependence is...
Fluorescence yields (FY) for the Ni $K$ and $L$ shells were determined by a theoretical an experimental group within framework of International Initiative on X-ray Fundamental Parameters (FPs) collaboration. Coster-Kronig (CK) parameters also measured shell Ni. Theoretical calculations same performed using Dirac-Fock method, including relativistic QED corrections. The values FY CK at PTB laboratory in synchrotron radiation facility BESSY II, Berlin, Germany, are compared to corresponding...
A theoretical study 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 nuclear charge range 1 =< Z 92 are obtained through use finite basis sets Dirac equation constructed B-splines. We also report spectral (energy) distributions several resonant transitions, which exhibit interesting structures, such as zeroes emission spectrum, indicating that strongly suppressed at certain...