Line broadening studies for Cr3+pairs and single ions in different oxide lattices

The electron-phonon coupling for Cr 3+ in different oxide host lattices (MgO, α-Al 2 O 3 and LaAlO 3 ) was probed by performing temperature dependent line broadening measurements for zero-phonon emission lines of single ions and exchange coupled pairs. No differences in electron-phonon coupling were found comparing the results for pairs and single ions in α-Al 2 O 3 (3NN and 4NN pairs) and LaAlO 3 (NN pairs). In Cr 3+ doped MgO (Cr 3+ -V Mg -Cr 3+ pairs), it was found that the electron-phonon coupling strength parameter is larger for the pairs than for the isolated Cr 3+ ions. This is probably due to changes in the surroundings of Cr 3+ by local charge compensation by a magnesium vacancy, and not to interaction between the Cr 3+ ions.