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弛豫动力学的特征。特别地，我们研究了碱卤化物中典型的固态缺陷F中心及其在多孔硅中的应用。在前一种情况下，我们测量并分析了KCl和RbCl中F中心的共振二次辐射光谱。在我们的研究结果中，从热发光（HL）的线性退极化行为中，我们发现光激发F中心的退激发机制仅发生在2p绝热势能槽（APET）中的晶格弛豫，直到普通发光的能量。此外，我们还测量了HL在OL区的激发能依赖性和温度依赖性，以澄清退极化的起源。在这个结果中，我们发现OL区域的HL分成两个元素，一个是激发时HL的P值相同（激发后2P - apet的晶格弛豫从高到低），另一个是P=0的发射（2P<热力学>势的底部OL）。这一结果与kayanumn计算的P的时间演化一致。在后者的情况下，我们从激发能依赖的角度研究了真空退火氧化多孔硅和解吸氢的蓝绿色光致发光动力学。我们通过考虑声子耦合和隧穿过程的局域激子模型从现象学上进行了解释。

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.