Soft-x-ray emission from Li-Al and Li-Mg alloys

The $K$-emission band of Li and $L_{23}$-emission bands of Mg and Al have been measured for Li-Mg and Li-Al prepared in a range of concentrations by either coevaporation or by evaporating thin films of Li on Mg(Al) substrates or Mg(Al) on Li substrates. The Li $K$ spectrum is nearly unchanged at all alloy concentrations in the Li-Mg system but broadens and develops a low-energy shoulder for large Al concentrations in the Li-Al system. Both Mg and Al $L_{23}$ spectra are narrower and more peaked at low energy in the equilibrium alloys than in the pure metals. The "many-body" threshold peaks on the Al and Mg $L_{23}$ spectra are generally suppressed by alloying with Li, except for low-temperature coevaporated Li-Al samples where the peak persists to very Li-rich alloys. Structure studies of these samples are required before the questions raised by these results can be fully resolved.