Double-vacancy excitations in the L atomic levels of neodymium

The x-ray absorption spectrum of neodymium exhibits discontinuities which are the results of multielectronic excitations in the L atomic shells of the elements. The observed discontinuities were identified as being the results of 2s^-1+2p1/2^-1, 2s^-1+2p3/2^-1, 2p1/2^-1+2p3/2^-1, 2p1/2^-2, and 2p3/2^-2 double excitations. Two discontinuities which correspond in energy to the simultaneous creation of three electronic vacancies were noted. The measured energies and the results of relativistic Hartree-Fock-Slater calculations for double-vacancy excitations are in good agreement. The magnitude of these discontinuities is difficult to determine with reasonable certainty, but it is only a few percent of the discontinuity and the L₃ absorption edge of the element.