Luminescence spectra and relaxation processes of ReCl 2? 6 in cubic crystals

Abstract

The Γ7(2T2g, t32g)→Γ8(4A2g) luminescence spectra, emissive life-times, excitation spectra and Γ8(4A2g)→Γ6(2T1g, t32g), Γ7Γ8(2T2g, t32g) absorption spectra of ReCl2–6 in A2SnCl6(A = K, Rb, Cs) and K2PtCl6 have been measured between 4 and 300 K. The absorption and luminescence spectra of each transition are dominated by three vibronic origins due to the ν6, ν4 and ν3 localised internal modes of the ReCl2–6 ion. The detailed structure near these origins shows features due to the coupling of band modes of the host to the localised modes. Every feature and the absorption and emission spectra of K2SnCl6: ReCl2–6 is doubled due to the low-temperature phase transition in the host. For the K2PtCl6 host the ReCl2–6 ion can be excited by energy transfer from the PtCl2–6 ion but the kinetics of the transfer are unusual.