KLedges in x-ray-absorption spectra of third-period atoms: Si, P, S, and Cl

A systematic investigation of double-electron KL-edge resonances in x-ray-absorption spectra of third-period atoms (Si, P, S, and Cl) is presented. Experimental data on ${\mathrm{NaH}}_2$ ${\mathrm{PO}}_4$, Graham’s salts (${\mathrm{Na}}_2$O:${\mathrm{P}}_2$ ${\mathrm{O}}_5$), ${\mathrm{Na}}_4$ ${\mathrm{P}}_2$ ${\mathrm{O}}_7$, elemental S, ${\mathrm{Na}}_2$ ${\mathrm{SO}}_3$, ${\mathrm{K}}_2$ ${\mathrm{SO}}_4$, ${\mathrm{CuSO}}_4$, ${\mathrm{Na}}_2$ ${\mathrm{S}}_2$ ${\mathrm{O}}_3$, ${\mathrm{Na}}_2$ ${\mathrm{S}}_2$ ${\mathrm{O}}_6$, ${\mathrm{NaClO}}_2$, ${\mathrm{NaClO}}_3$, and ${\mathrm{NH}}_4$ ${\mathrm{ClO}}_4$ are reported and discussed in combination with previous measurements at the Si KL edge of Si${\mathit{X}}_4$, (X=H,${\mathrm{CH}}_3$,Br,Cl,F) molecules. The further comparison of these results with KL-edge structures in Ne and Ar provides an almost complete overview of these excitations for third-period atoms. A compilation of energies and oscillator strengths for the dominant resonances is reported and the main trends of energy splitting, intensity, and energy position versus oxidation state and Z number are discussed.