1s−2pTransitions in Mg Bombarded with 21-MeV Oxygen Ions

A thick Mg target was bombarded by a 21-MeV oxygen-ion beam. Nine $1s-2p$ transitions were observed with an energy resolution of 1.26 eV. Relative to the 1253.6-eV $K{\alpha }_{1,2}$ reference energy, the energies of the other observed transitions in units of eV were 1261.5, 1268.5, 1270.7, 1273.3, 1281.0, 1283.0, 1293.0, and 1295.4. By comparing with Hartree-Fock-Slater calculations, the five groups of peaks were found to correspond to $1s-2p$ ($K\alpha$) transitions with initial configurations ${\mathrm{}\left(1s\right)\mathrm{}}^{-1\mathrm{}}{\mathrm{}\left(2p\right)\mathrm{}}^{-n}$ for $n=0, 1, 2, 3, \mathrm{and} 4$. The transition for the ${\mathrm{}\left(1s\right)\mathrm{}}^{-1\mathrm{}}{\mathrm{}\left(2p\right)\mathrm{}}^{-5\mathrm{}}$ initial configuration was not observed in this experiment. This can be attributed to self-absorption in the target since the ${\mathrm{}\left(1s\right)\mathrm{}}^{-1\mathrm{}}{\mathrm{}\left(2p\right)\mathrm{}}^{-5\mathrm{}}$ $K\alpha$ transition energy lies above the $K$ absorption edge.