RAMAN-SCATTERING OF NEAT AND MIXED-CRYSTALS OF IRF6 - JAHN-TELLER INTERACTION IN THE GROUND-STATE

Raman scattering data for neat and mixed crystal IrF6 samples at 77 K are reported. It is found that v2(eg) and v5(t2g) both evidence non-vanishing Jahn-Teller interactions for the T8g (4A2g) ground state. The linear Jahn-Teller parameters for these modes are D2≤ 0.001 and D5 = 0-02. The v5 Jahn-Teller interaction is large enough to quench an expected exciton splitting of ~ 20 cm-1 almost completely. The v2 Jahn-Teller interaction is small enough so that exciton interactions predominate; however, normal v2 k = 0 sharp line exciton structure is not observed. Anomalous phonon behaviour is observed and discussed with respect to other hexafluoride phonon data. The non-Jahn-Teller active modes v1 v3, v4, v6 are found to behave in a fashion consistent with other members of this series. © Taylor & Francis Group, LLC.