Excitonic energy transfer to the 3d electrons of ${\mathrm{Mn}}^{2+}$sin ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$ Te

We studied the energy transfer between excitons and the 3d electrons of ${\mathrm{Mn}}^{2+}$ in ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$ Te crystals within a Mn concentration range of 0.2⩽x⩽0.45 at T=2, 5, and 20 K by emission, excitation, and time-resolved photoluminescence measurements. Time-integrated emission spectra show a strong quenching of the ${\mathrm{L}}_2$ -type exciton luminescence together with a strong increase of intensity of the ${}_{}{}^4{}_{}{}^{}$ ${\mathrm{T}}_1$ (G)${\to }^6$ ${\mathrm{A}}_1$ (S)${\mathrm{Mn}}^{2+}$ luminescence if the Mn concentration is raised from x=0.32 to 0.43. Excitation spectra of the ${}_{}{}^4{}_{}{}^{}$ ${\mathrm{T}}_1$ (G)${\to }^6$ ${\mathrm{A}}_1$ (S) ${\mathrm{Mn}}^{2+}$ luminescence give evidence of an excitonic energy transfer via free and intrinsically localized excitons to the 3d shell of ${\mathrm{Mn}}^{2+}$ . By time-resolved photoluminescence measurements we investigated the lapse of luminescence at discrete energies in the exciton luminescence band using pulsed band-to-band excitation. The luminescence shows a nearly exponential decay. We see a strong decrease of the luminescence decay time when the ${\mathrm{Mn}}^{2+}$ ions act like energy absorbers for the exciton energies.