L23soft-x-ray emission and absorption spectra of Na

Abstract

The $L_{23}$ soft-x-ray emission (SXE) and soft-x-ray absorption (SXA) edges have been measured. The SXE edges were measured at temperatures between 85 and 380 K, and analyzed to obtain edge positions and widths. The widths increased from ${\Gamma }_{\mathrm{SXE}}=100\mathrm{}$ meV at 85 K to 150 meV at 320 K and to 180 meV above the melting point at 380 K. Both SXE and SXA edges were measured at 100 K with the same spectrometer, and the data were analyzed to obtain values of the edge widths (${\Gamma }_{\mathrm{SXE}}=100\mathrm{}$ meV and ${\Gamma }_{\mathrm{SXA}}=64\mathrm{}$ meV), of the many-body peaking parameter (${\alpha }_{\mathrm{SXE}}=0.15\mathrm{}$ and ${\alpha }_{\mathrm{SXA}}=0.24\mathrm{}$), of the gap between the edges ($E_g=74\mathrm{}$ meV), and of the excess width of the emission edge [${\left(\Delta \Gamma \right)}^2={\Gamma }_{\mathrm{SXE}}^2-{\Gamma }_{\mathrm{SXA}}^2=5900\mathrm{}$ ${\mathrm{}\left(\mathrm{meV}\right)\mathrm{}}^2$]. The values of $E_g$ and ${\left(\Delta \Gamma \right)}^2$ were used in the partial-lattice-relaxation theory of Almbladh to obtain a value of the core-hole lifetime broadening (${\Gamma }_{2p}=10\mathrm{}$ meV). We conclude that structure in the transition density of states, many-body effects, and lattice relaxation all have important effects on the edge structure, and suggest that rounding of the SXE edge by partial relaxation accounts for the smaller peaking parameter obtained from the SXE data as compared to the SXA data.