Luminescent VUV spectroscopy of Er3+ and Tm3+ ions in strontium fluoride crystals

Emission and excitation spectra as well as decay curves of Er3+ and Tm3+ ions doped into SrF2 crystals have been studied using time-resolved vacuum-ultraviolet spectroscopy under pulsed synchrotron radiation at 8 K. In emission spectrum for crystals doped with Er3+ ions together with well-known emission caused by spin-forbidden 4f105d→4f11 transitions (decay constant in the microsecond range), a new fast emission band detected at 146.5 nm (decay constant is less than 0.6 ns) has been revealed. It was shown that excitation spectra of f-f and d-f emission bands for Er3+ and Tm3+ ions in SrF2 have opposite behaviors in the spectral range corresponding to energy of their 4fn-15d configurations. These peculiarities and energy transfer mechanisms were analyzed.