XPS study of the exchange-splitting in the s-levels of Mn and R in RMn2Si2 (R = La to Nd, Sm and Gd)

Structure of X-ray photoelectron spectra of lanthanide compounds

“…Thus, it became possible to detect, with a relatively high accuracy, slight changes in the unpaired electron density (Dr) on a metal ion in a dielectric material and to estimate semi-quantitatively the Dr value using the XPS method. An increase in the number of unpaired electrons in a 3d-metal or lanthanide ion in a compound by one electron (Dr = 1e 7 ) is known 44,93,94,196 to increase the splitting of the M3s or Ln4s line by approximately 1 eV (see, for example, Fig. 29).…”

“…The observed line broadening is assumed to be mainly due to charge induction (Dr) onto the Nb 5+ ion, and, on passing from a-Nb 2 O 5 to LnNbO 4 (Ln are lanthanides from the medium of the row), the Nb 5+ ion electronic configuration changes appreciably from {4d } to {4d Dr }. It has been noted 44,93,94,196 that the multiplet splitting arises with the highest probability in the spectra of core electrons having the same principal quantum number as the unpaired electrons. In this case, the most pronounced multiplet splitting should be expected in the spectra of the Nb4s electrons.…”

“…The Ln5s spectra of lanthanide compounds exhibit, in the simplest case, a structure related to multiplet splitting (DE ms ). 44,93,94 In this case, two components arise instead of the expected single line; the splitting is proportional to the number of unpaired Ln4f electrons. The greatest multiplet splitting was observed for the lanthanide trifluorides of the middle of the lanthanide row, the maximum value being found for GdF 3 : DE ms (Gd 3+ ) = 3.2 eV (see Fig.…”