EXCITED STATES OF 3d-ELECTRON AND LATTICE RELAXATION IN SEMIMAGNETIC-SEMICONDUCTORS

在低温下观察到Mn^<2+>光致发光峰的能量随激发能的变化。利用这一位移，我们分别估计了Mn^<2+>光致发光的非均匀和均匀展宽。随着温度的升高，非均匀展宽的性质转变为均匀性质。研究了红外光致发光的时间分布，并利用从扩展态到局域态的能量转移解释了其建立过程。在2K下研究了Mn^<2+>的激发d多重态的高密度效应，在高密度激发下观察到非指数衰减。在衰减曲线的初始阶段，出现了寿命较短的额外衰减，衰减强度增大。这种效应被认为是超荧光或超辐射的前兆效应。

The energy shift of the Mn^<2+> photoluminescence peak according to excitation energy is observed at low temperatures. Using this shift we estimate inhomogeneou and homogeneous broadening of Mn^<2+> photoluminescence separately. In creasing temperatures inhomogeneous broadening changes its character to homogeneous one. Time profiles of infrared photoluminescence are investigated and their built up processes are explained using energy transfer from the extended states to localized states. High density effects of excited d-multiplet states of Mn^<2+> are investigated at 2K and nonexponential decay are observed at high density excitation. At the initial part of the decay profiles extra decay with short life time appear and its intensity increases. This effect is considered as the precursor effect of super flourescence or super radiance.