Browsing by Author "Ejigu, Afrash"

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    Energy Transfer Between Excitons and the 3d-Electrons of Mn2+ In Zn1_Xmnxse
    (Addis Ababa, Ethiopia, 1995-06) Ejigu, Afrash
    In this thesis the excitation spectra of the 4TI ---+ 6 Al emission of Mn2 + in Znl . .Mr\Se crystals and their dependence on the crystal temperature, intensity of the exciting laser and manganese concentration (x $ 0.016) are investigated. Eventhougth some of the excitation spectra of these crystals were published in literature the origin of one of the excitation band ( M-band ) still remains unknown. The M-band is an excitation band of the 4TI ---+ 6AI emission of Mn2 + in Znl.MnxSe within the spectral range of bound excitons. Computer fitting techniques were used to determine some important parameters of the M-band and the bound exciton band (BE-band). F rom the comparison of the crystal temperature, exciting laser intensity and Mn concentration dependence of some of these fitting parameters of the M-band with that of the BE-band it is found that the M-band is built up of a multiple of bound excitons, which are different from that of the BE-band.
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    Energy Transfer Between Excitons and the 3d• Electrons of mn2+ in zn1-xmnxse
    (Addis Ababa University, 1995-06) Ejigu, Afrash; U. Stutenbaumer
    In this thesis the excitation spectra of the 4T I ~ 6 Al emission of Mn2+ in Znl.,Mn.Se crystals and their dependence on the crystal temperature, intensity of the exciting laser and manganese concentration (x «; 0.016) are investigated. Eventhougth some of the excitation spectra of these crystals were published in literature the origin of one of the excitation band ( M-band ) still remains Iillknown. The M-band is an excitation band of the 'TI ~ 6AI emission of Mn2+ in Znt.,Mn.Se within the spectral range of bound excitons. Computer fitting teclmiques were used to detennine some important parameters of the M-band and the bound exciton band (BE-band). 1) From the comparison of the crystal temperature, exciting laser intensity and Mn concentration dependence of some of these fitting parameters of the M-band with that of the BE-band it is found that the M-band is built up of a multiple of bound excitons, which are different from that of the BE-band