Line broadening studies for isoelectronic divalent and trivalent lanthanides

Temperature-dependent line broadening measurements are reported for transitions on Sm2+ and Eu3+ (4f 6) and Eu2+ and Gd3+ (4f 7). Analysis of the results shows that the electron–phonon coupling parameter ᾱ derived from a fit of the line width data to a two-phonon Raman dephasing process are similar for the divalent and trivalent lanthanides. The low energy of the opposite parity 4f n−15d1 state for the divalent lanthanides does not result in a significant difference in temperature-dependent line broadening. This indicates that an extrinsic Raman two-phonon dephasing process involving an opposite parity intermediate state is not responsible for the observed line broadening.