Electron-phonon coupling in Ni²⁺-doped MgGa₂O₄ spinel

Ni²⁺-doped MgGa₂O₄ crystals, with spinel structure, have been reported as promising candidates as active media for broadband optical amplifiers and tunable laser systems in the visible and near infrared regions. In this paper we present and discuss the interaction between electronic transitions of divalent nickel ions and vibration modes of the host lattice MgGa₂O₄ (electron-phonon interaction), which is responsible for the wide absorption and emission broad-bands. The Huang-Rhys parameter S=3.18, the breathing phonon-energy h{stroke}ω =387 and the Zero Phonon Line (ZPL) position at 8 850 cm^-1 (all estimated in the framework of the single configurational coordinate model and harmonic approximation) are reported. To check the reliability of the obtained values for S and h{stroke}ω the emission band modeling has been performed. Good agreement between theoretical and experimental emission spectra and the closeness between theoretical and experimental values of the ZPL energy confirms validity of the estimated parameters of electron-phonon interaction for MgGa₂O₄: Ni²⁺system.