MnO 4− and MnO 42− molecular centers in cubic lattice: near infrared luminescence and resonance Raman spectra

Abstract

We report the first observation of the near-infrared luminescence in RbI crystals doped with the MnO 4 2− (manganate) and MnO 4 − (permanganate) ions. NIR luminescence spectra of the MnO 4 − and MnO 4 2− ions show similarity in both the spectral region (8500–11 000 cm −1) and the appearance of well-resolved vibronic structure at 4 K caused by the electron coupling with the bending (e) modes of the impurity ions. This fine structure is considered as a result of e⊗e and t 2⊗e Jahn–Teller effect in the ground and excited electronic states, respectively. MnO 4 2− NIR luminescence is attributed to the d–d ( 2T 2→ 2E) transition of a single d-electron of Mn 6+.. The origin of the luminescence in case of MnO 4 −-doped iodides is connected with the transient Mn 6+ state, which is generated by the illumination-induced charge transfer process. The possibility of thermal population of Mn d-orbitals in case of MnO 4 − ion is also discussed.