A multiplatform code for the analysis of energy-dispersive X-ray fluorescence spectra

The present status of the field of fluorescence yields, radiationless (Auger and Coster-Kronig) and radiative transition probabilities is summarized. Tables of experimental and theoretical results are included, and tables of "best values" of important quantities are presented.

X-Ray Fluorescence Yields, Auger, and Coster-Kronig Transition Probabilities

Following the introduction of GUPIXWIN in 2005, a number of upgrades have been made in the interests of extending the applicability of the program. Extension of the proton upper energy limit to 5 MeV facilitates the simultaneous use of PIXE with other ion beam analysis techniques. Also, the increased penetration depth enables the complete PIXE analysis of paintings. A second database change is effected in which recently recommended values of L-subshell fluorescence and Coster–Kronig yields are adopted. A Monte Carlo code has been incorporated in the GUPIX package to provide detector efficiency values that are more accurate than those of the previous approximate analytical formula. Silicon escape peak modeling is extended to the back face of silicon drift detectors. An improved description of the attenuation in dura-coated beryllium detector windows is devised. Film thickness determination is enhanced. A new batch mode facility is designed to handle two-detector PIXE, with one detector measuring major elements and the other simultaneously measuring trace elements.

The Guelph PIXE software package IV

High resolution 1s core hole X-ray spectroscopy in 3d transition metal complexes—electronic and structural information

Excitations of the $2p$ subshell in the $3d$ transition metals and their oxides have been studied by inelastic scattering of 75-keV electrons. The ${L}_{23}$ "white lines" which arise from dipole transitions to unoccupied $d$ states have been investigated in terms of their threshold energies, widths, and intensity ratios. Shifts in the ${L}_{3}$ threshold energy between the metal and oxide are different from the chemical shifts measured by x-ray photoemission spectroscopy and this suggests the importance of relaxation effects. Single-particle calculations for the ${L}_{3}$ spectra are also discussed. Measured ${L}_{3}$ linewidths are generally larger than those predicted by suitably broadened theory. A variation from the statistical ${L}_{3}$-to-${L}_{2}$ white-line intensity ratio of 2:1 has been observed across the $3d$ transition row, with values ranging between 0.8:1 for Ti to 5:1 for FeO. This behavior appears to be associated with the white lines since Cu with a filled $3d$ band exhibits the statistical results. It is suggested that the anomalous ratios may be explained by a breakdown of $j\ensuremath{-}j$ coupling caused by an exchange mechanism. Finally, the extended x-ray absorption fine-structure-type structure extending several hundred eV above the white lines is analyzed for Cr to provide the radial distribution function.

Study of the L 23 edges in the 3 d transition metals and their oxides by electron-energy-loss spectroscopy with comparisons to theory

A comprehensive set of theoretical $L$-shell Auger and total widths, and Coster-Kronig and fluorescence yields is presented for atomic numbers $18\ensuremath{\le}Z\ensuremath{\le}100$. These quantities are based on ab initio relativistic calculations. Agreement with experimental values is fair for ${\ensuremath{\omega}}_{1}$ and generally good for ${\ensuremath{\omega}}_{2}$, ${\ensuremath{\omega}}_{3} (Z\ensuremath{\ge}54)$, ${f}_{23} (Z\ensuremath{\ge}60)$, $\ensuremath{\Gamma}({L}_{2})$, $\ensuremath{\Gamma}({L}_{3})$, and for $\ensuremath{\Gamma}({L}_{1})$ in the range $49\ensuremath{\le}Z\ensuremath{\le}75$. Discrepancies in $\ensuremath{\Gamma}({L}_{1})$ for $Zl49$ point toward the need for a many-body calculation of low-energy ${L}_{1}\ensuremath{-}{L}_{2,3}{M}_{4,5}$ Coster-Kronig transitions. There is a pronounced need for measurements of ${\ensuremath{\omega}}_{3}$ and ${f}_{23}$ of elements lighter than Xe.

Widths and fluorescence yields of atomic L -shell vacancy states

Relativistic Radiationless Transition Probabilities for Atomic K- and L-Shells

: X-Ray and Auger transition probabilities were calculated for atoms that have been singly and multiply ionized in inner shells. The effects of relativity and configuration interaction on these rates were studied, and lifetimes of atomic inner-shell holes were computed. Synchrotron radiation was employed for precision measurements of atomic level energies, for the study of inelastic scattering, and for the investigation of sub-threshold excitation of atomic hole states. (Author)

Atomic inner-shell processes

Average $L$- and $M$-shell-vacancy distributions produced in the deexcitation of atoms that have been singly ionized in the $K$ shell or one of the $L$ subshells are derived from a comprehensive set of available experimental and theoretical data on radiative- and Auger-transition rates. The data are supplemented by new calculations in $j\ensuremath{-}j$ coupling from nonrelativistic screened hydrogenic wave functions of the following radiationless transition rates: $K\ensuremath{-}LL$, $K\ensuremath{-}LM$, and $K\ensuremath{-}LN$ for selected elements with $20\ensuremath{\le}Z\ensuremath{\le}81$, and ${L}_{i}\ensuremath{-}MM$, ${L}_{i}\ensuremath{-}MX$, and ${L}_{i}\ensuremath{-}XY$ for $26\ensuremath{\le}Z\ensuremath{\le}93$. Experimental and theoretical data on Auger- and radiative-transition probabilities are critically compared. Auger-electron intensity ratios and $\frac{K{\ensuremath{\alpha}}_{2}}{K{\ensuremath{\alpha}}_{1}}$ and $\frac{K\ensuremath{\beta}}{K\ensuremath{\alpha}}$ x-ray intensity ratios from a best fit to experimental data are tabulated for even atomic numbers from 20 to 94. The probability, per initial $K$ vacancy, of vacancy production in each ${L}_{i}$ subshell is derived from experimental data and tabulated for $20\ensuremath{\le}Z\ensuremath{\le}94$; components due to Auger and x-ray transitions are listed separately. These probabilities agree well with purely theoretical vacancy distributions also derived here. The probability of $M$-shell-vacancy production in the decay of $K$ and ${L}_{i}$ vacancies is derived from theory and tabulated for selected atoms with $16\ensuremath{\le}Z\ensuremath{\le}93$.

Atomic Vacancy Distributions Produced by Inner-Shell Ionization

Radiationless transition probabilities to the atomic $1s$ shell are calculated for all transitions that contribute measurably to the Auger effect. Screened nonrelativistic hydrogenic wave functions are used. The effective charge for the continuum-electron Coulomb wave function is taken to be the geometric mean of the effective charges appropriate for the state from which the electron originates and the next-higher state. The results are combined with Scofield's radiative transition probabilities to derive theoretical $K$-shell fluorescence yields. Agreement with a selected set of most reliable ${\ensuremath{\omega}}_{K}$ measurements is very good in the range from $Z=10 \mathrm{to} 55$, and total $K$-level widths agree very well with measured values.

Mau Hsiung Chen

Papers

Widths and fluorescence yields of atomic L -shell vacancy states

Relativistic Radiationless Transition Probabilities for Atomic K- and L-Shells

Atomic inner-shell processes

Atomic Vacancy Distributions Produced by Inner-Shell Ionization

Atomic Radiation Transition Probabilities to the1sState and TheoreticalK-Shell Fluorescence Yields