THE STUDY OF DYNAMICAL PROCESS IN OPTICALLY EXCITED STATES USING TIME-RESOLVED POLARIZATION SPECTROSCOPY

利用皮秒时间分辨偏振光谱研究了光激发态的驰豫动力学特性。特别是，我们研究了碱金属卤化物中的F心这一典型的固态缺陷及其应用中的多孔硅，在前者中，我们测量和分析了KCl和RbCL中F心的共振二次辐射光谱。在我们的结果中，从热发光(HL)的线性退偏振行为中，我们发现光激发F心的退激机制仅通过2p绝热势能槽(APET)中的晶格弛豫发生，直到普通发光的能量为止。此外，我们还测量了HL在OL区的激发能量依赖关系和温度依赖关系，以阐明退偏振的来源。在这一结果中，我们发现在OL区的HL分为两个元素，即在激发(2p-APET中的晶格弛豫从激发后的高能到低能)和P=0的发射(2P&lt；热力学和gt；势中从下到下的OL)中HL的P值相同。这一结果与Kayanuma计算的P随时间的演化相一致。在后一种情况下，我们从激发能量依赖的角度研究了多孔硅在真空退火氧化和脱附氢气中的蓝绿光致发光的动力学。我们用一个考虑了声子耦合和隧穿过程的局域激子模型进行了唯象解释。

We investigated the features of relaxation dynamics in optical excited states by using picosecond time-resolved polarization spectroscopy. Particularly, we investigated an F center in alkali halides which is typical defect in solid state and a porous silicon in its application.In the former case, we measured and analyzed the spectrum of resonant secondary radiation for the F center in KCl and RbCl. In our results, from the behavior of linear depolarization for the hot-luminescence (HL), we found that the de-excitation mechanism of the optically excited F center occurs solely through lattice relaxation in a 2p adiabatic potential energy trough (APET) until the energy of ordinary luminescence. Moreover, we measured the excitation energy dependence and temperature dependence for HL in OL region to clarify the origin of the depolarization. In this result, we found that the HL in the OL region separates into two elements, that is, one is the same value of P of the HL in the excitation (lattice relaxation in a 2p-APET from high to low energy after excitation) and the emission with P=0 (OL from bottom in 2P<thermodynamics> potential). This result consists with the time evolution of P calculated by KayanumaIn latter case, we investigated the dynamics of the blue-green photoluminescence from porous silicon oxidized in vacuum-annealing and desorpted hydrogen in terms of excitation energy dependence. We explained phenomenologicaly by a localized exciton model which takes into account the phonon coupling and tunneling processes.