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Mn 3d states in Znl Mn"Y (Y=S,Se,Te) have been investigated using resonant synchrotronradiation photoemission at the Mn 3p-3d threshold. We observe chemical trends due to anion substitution for the main Mn 3d photoemission feature at 3.5, 3.6, and 3.8 eV below the valence-band maximum as well as for the d( f )-d( $ ) exchange splitting for Zno»Mno»S, Zno 8lMno l9Se, and Zno «MnQ 32Te, respectively. The size of relaxation effects associated with the resonant-photoemission process is derived.Valence-band offsets of 0.3 eV are found between the semimagnetic Zn compounds and their parent binary alloys.

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Luminescent properties of Eu'+ or Ce3+ doped Sffia~S4 powder samples are investigated over the temperature range 30 to 300 K. Up to 300 K the lifetime remains constant (TO = 480 and 24 ns for Eu '+ and Ce3+, respectively) showing that the probability of non-radiative transitions is negligible at room temperature. The decay of thin films prepared by reactive radio-frequency magnetron sputtering deviates strongly from an exponential one as a consequence of energy transfer to defects. Codoping of Ce3' with Na+ considerably increases the luminescence efficiency.Les proprittts luminescentes de poudres de SrGazS4 doptes au Eu2+ et au Ce3+ sont ttudites pour des temptratures variant de 30 h 300 K. Jusqu'h 300 K, les durkes de vie restent invariantes (zo = 480 et 24 ns pour Eu2+ et Ce3+ respectivement). Ceci montre que les probabilitts de transitions non-radiatives sont ntgligeables h la tempkrature ambiante. Le dtclin de couches minces prtpartes par pulvtrisation cathodique radio-frtquence est beaucoup plus rapide et montre la prbsence d'un transfert d'tnergie vers des dtfauts. Le codopage de SrGazS4 : Ce3+ avec du Na+ ambliore fortment le rendement de luminescence.