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Mid-IR random lasing of Cr-doped ZnS nanocrystals

The laser ablation method enabled fabrication of transition-metal (Cr, Co, Fe)-doped nanocrystals with a strong photoluminescence over a 2–5 µm spectral range. The first room temperature mid-IR random lasing due to impurity intra-shell transitions in transition-metaldoped semiconductor nanocrystals is reported. Temperature dependences of the lasing spectra reveal diverse behaviour of the output spectra for powders of different grain sizes.