Estimation of the ratio of double and single Auger transition rates for the L shell of Kr, Nb and Gd

Abstract

Double and single Auger transition rates for the L shell of Li-like Kr, Nb and Gd ions are calculated using multiconfiguration Dirac-Fock bound-state wavefunctions. From these rates, the ratio of the cross sections for the corresponding resonant electron-transfer double-excitation and resonant electron-transfer excitation processes are derived. The values we obtained for these ratios are of the order of 10 −7 , consistent with recent experimental results.

Collective relaxation processes in atoms, molecules and clusters

“…To our knowledge, there is no direct observation of CAD in high-Z atoms, which could be compared to this result. However, considering that the experimental value represents an upper limit, it is in reasonable agreement with the R 3 ratio of 2.8 × 10 −7 , calculated by Marques and coworkers [13]. These results indicate that in high-Z atoms the significance of CAD drops significantly by about two orders of magnitude.…”

“…The shake-off mechanism was not included, but since with increasing atomic number the 1s f |2s i overlap decreases the approach is justified. Indeed, for the two-electronone-photon radiative transition, the effects of relaxation were estimated to account for about 20% and only 8% of the total intensity for Z = 36 and Z = 54, respectively [13]. Similar trends can be expected also in radiationless transitions.…”

“…The CAD electron is in this case emitted with an energy of about 105 eV, compared to about 582 eV for the dominant CAD transition of type I in Ar 2+ (2s −2 ). Valuable insight into the mechanism of CAD is provided by the theoretical papers of Vaeck and Hansen [14] and of Marques et al [13] who studied CAD in low-Z and high-Z atoms respectively. In double K-hole states of low-Z atoms, the main contribution to the CAD process stems from the 2s → 1s shake-down (SD) mechanism accompanying normal K − LL Auger transition.…”

“…Marques et al [13] focused on high-Z atoms and calculated the AD and CAD rates for lithium-like Kr, Nb and Gd ions with all three electrons in the L-shell. The rates were computed using multiconfigurational Dirac-Fock (MCDF) bound-state wave functions.…”

Three-Electron Auger Process from Beam-Foil Excited Multiply Charged Ions

“…These studies triggered several theoretical investigations (see [7,8], and references therein) for low-Z ions. More recently, also high-Z ions were investigated theoretically [9], and upper cross section limits for the time-reversal process of the three-electron Auger process, the ''trielectronic recombination'' were obtained with a channeling technique [10]. These rare three-electron processes are of fundamental interest for the study of three-electron correlation in bound systems [10], they are forbidden in independent particle models like Hartree-Fock and become allowed only in the many-body approach [7][8][9].…”