Two-electron-one-photon transition in aluminum following double-K-shell ionization.

Abstract

The decay possibilities of atoms with two K-shell vacancies have been studied by bombarding a thin (465 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$) Al target with electrons of ${E}_{0}$=20 keV. In addition to the more common probability involving a sequential decay [which leads to a ${K}^{\mathrm{\ensuremath{-}}2}$\ensuremath{\rightarrow}${K}^{\mathrm{\ensuremath{-}}1}$${L}^{\mathrm{\ensuremath{-}}1}$ transition with the emission of a K\ensuremath{\alpha} hypersatellite x ray, called the one-electron--one-photon transition (OEOP)], we have also investigated the weakly correlated two-electron--one-photon transition (TEOP) by spectroscopy of the emitted x rays using a high-resolution crystal spectrometer. The two transitions were recorded with different crystals always relative to the intensity of the K\ensuremath{\alpha} line, which originates from a single-K-shell vacancy. The branching ratio ${R}_{B}$=${I}_{\mathrm{TEOP}/{I}_{\mathrm{OEOP}}}$ was found to be ${R}_{B}$=(2.2\ifmmode\pm\else\textpm\fi{}0.8)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$, which is in good agreement with theoretical predictions, that include the electron correlation approximately and is close to previous heavy-ion induced investigations.