Dynamic Jahn‐Teller effect in the excited states of SeCl₆²⁻, SeBr₆²⁻, TeCl₆²⁻ and TeBr₆²⁻: Interpretation of electronic absorption and Raman spectra

Abstract

Abstract Although the complex‐ions SeCl 6 2− , SeBr 6 2− , TeCl 6 2 − and TeBr 6 2− are regular octahedral, the infrared spectra show that some evidence is present for vibronic coupling between ground state and first excited state (dynamic second order Jahn‐Teller effect). The electronic absorption spectra are reported and assignments given. The splittings of the absorption bands closely resemble those found in the spectra of the alkali halide phosphors (KCl: Tl+ etc.). As for the phosphors, an explanation is given in terms of a dynamic Jahn‐Teller effect in the excited states. In connection with this, attention is paid to the unusual intensities of the Jahn‐Teller active modes (e g and t 2g ) in the Raman spectra of these complex‐ions.