Temperature dependence of spectral positions and widths of 5DJ → 7FJ fluorescence lines originating from Sm2+ ions in SrFCl crystals

The temperature dependence of the spectral positions and widths of the photoluminescence lines corresponding to the 5D0 → 7F0, 5D0 → 7F1 and 5D1 → 7F0 electronic transitions in Sm2+-doped SrFCl crystal was measured between 87 and 625 K at ambient pressure. The temperature dependence of the homogeneous line width Γh(T) for all these transitions in the whole temperature range used can be described by the two-phonon Raman scattering of acoustic phonons with the Debye temperature TD ≈ 230 K. Comparison of the temperature- and pressure-induced shifts revealed why all the emission lines studied show the blue temperature shifts. It is so because a greater part of the line shift is caused by the thermal expansion of the host crystal and not by enhancement of the electron–phonon coupling with increasing temperature.