Single-photon two-electron rearrangement transitions

Abstract

The observation and identification of $K$ x rays resulting from one-photon two-electron rearrangement are made for Mg, Al, and Si following heavy-ion bombardment. Two types of rearrangement processes, which lead to $K$ x rays below the energy of the characteristic $K\ensuremath{\alpha}$ x ray, are delineated: the radiative Auger effect (RAE) and radiative electron rearrangement (RER). The RAE process previously described by \AA{}berg and Utriainen competes with the characteristic $K\ensuremath{\alpha}$ x ray. The observed energies and relative intensities $\frac{\mathrm{RAE}}{K\ensuremath{\alpha}}$ from heavy-ion bombardment agree with those from electron and photon excitation. The RER process which we have recently proposed is the emission of a photon from the ${(1s)}^{\ensuremath{-}1}{(2p)}^{\ensuremath{-}n}$ to ${(2s)}^{\ensuremath{-}2}{(2p)}^{\ensuremath{-}n+1}$ electron rearrangement for $n=1\ensuremath{-}6$. This model gives good agreement between measured and Hartree-Fock calculated RER energies. $K{L}^{n}$ RER and $K\ensuremath{\alpha}{L}^{n}$ satellites are competing decay branches of the ${(1s)}^{\ensuremath{-}1}{(2p)}^{\ensuremath{-}n}$ initial configuration. The $\frac{(K{L}^{n}\mathrm{RER})}{K\ensuremath{\alpha}{L}^{n}}$ branching ratios are measured. The RER transitions are shown to be allowed by configuration mixing of final states with the same spin and parity. The branching ratio is a product of the mixing coefficient and a ratio of fluorescence yields. The theoretical branching ratios $\frac{(K{L}^{1}\mathrm{RER})}{K\ensuremath{\alpha}{L}^{1}}$ and $\frac{(K{L}^{2}\mathrm{RER})}{K\ensuremath{\alpha}{L}^{2}}$ are calculated and compared to experiment.