Double-vacancy excitations in theLatomic levels of Pr and Sm

Discontinuities resulting from the simultaneous creation of two electronic vacancies in the $L$ atomic shells of praseodymium and samarium were observed in the x-ray absorption spectra of these elements. These discontinuities were identified as being the results of the double excitations ($2s^{-1\mathrm{}}+2\mathrm{}{p}_{\frac{1}{2}}^{-1\mathrm{}}$), ($2s^{-1\mathrm{}}+2\mathrm{}{p}_{\frac{3}{2}}^{-1\mathrm{}}$), and ($2p_{\frac{1}{2}}^{-1\mathrm{}}+2\mathrm{}{p}_{\frac{3}{2}}^{-1\mathrm{}}$), and their measured energies were found to be in good agreement with the results of relativistic Hartree-Fock-Slater calculations. The magnitude of these discontinuities, although difficult to determine, is about fifty times smaller than the magnitude of the discontinuity at the $L_3$-absorption edge of the element.