EPR and optical spectroscopy of the Tm2+ ion in the KMgF3 single crystal

► Tm2+ ion in the KMgF3 single crystal has been studied by EPR and optical spectroscopy. ► Stark level energies of the cubic Tm2+ multiplets have been established. ► crystal field parameters of the cubic Tm2+ in KMgF3 have been calculated. ► Information about the phonon spectra of KMgF3 crystals has been obtained from optical spectra.