Investigation of Inhomogeneous Broadening of Optical Spectra of Localized Centers in Solids by Monochromatic-Light-Induced Fluorescence

当光谱中的非均匀展宽很明显时，例如玻璃和聚合物中的局域电子，只有在消除这种非均匀展宽的影响后才有可能获得详细的信息。我们研究了一种通过观察样品在单色光激发下的荧光来消除光谱不均匀展宽的方法。特别是在凝聚态染料分子中，由于荧光衰减时间短，散射激发光和荧光难以区分。我们已经证明，通过结合来自连续波锁模激光器的超短光脉冲和时间相关单光子计数方法，这是可能的。事实上，我们第一次成功地测定了选择性荧光光谱，包括聚合物中的窄共振线和蛋白质中的发色团。该方法获得了无序体系中杂质分子的均相和非均相光谱的许多信息，如位点-能量分布和单位点荧光光谱。本文还对Eu^<3+>掺杂材料的激光诱导荧光实验进行了详细分析。研究表明，我们可以根据选择的荧光特性确定作用于稀土离子的各种转变机制以及晶体场参数的分布。本文还证实了基于Eu^<3+ b>离子的波函数可以一致地理解所有数据，包括激光诱导荧光的光谱形状及其与激发波长的关系。将Eu^<3+>掺杂玻璃和聚合物中的激光诱导荧光光谱与Eu^<3+>掺杂晶体中的施加压力实验进行了比较，证实了位置选择性荧光方法的有效性。少

When the inhomogeneous broadening is significant in the optical spectra, such as in the case or localized electrons in glasses and polymers, it is possible to obtain detailed information only after the elimination of the effect of this inhomogeneous broadening. We have studied a method to eliminate inhomogeneous broadening in optical spectra by observing fluorescence from the sample which is excited by monochromatic light. Especially, it has been aimed to apply this site-selective fluorescence method to dye molecules in condensed matter, in which the discrimination between the scattered exciting light and fluorescence is difficult because of the short fluorescence decay time. We have shown that this is possible by combining ultra-short optical pulses from a cw mode-locked laser and a time-correlated single-photon counting method. In fact, we have succeeded, for the first time, in the d etermination of the site-selected fluorescence spectrum including the narrow resonance line in dye mo … More lecules in polymers and chromophores in proteins. Much information on the homogeneous and inhomogeneous spectra of impurity molecules in disordered systems, such as the site-energy distribution and single-site fluorescence spectra, has been obtained using this method.Detailed analysis of the laser-induced fluorescence experiments in Eu^<3+>-doped materials has also been performed. It has been shown that we can determine various transition mechanisms as well as the distribution of the crystal-field parameters acting on the rare earth ion from the site-selected fluorescence characteristics. It has also been confirmed that all the data including the spectral shape of the laser-induced fluorescence and its dependence on the excitation wave-length are understood consistently by basing on the wave functions of the Eu^<3+> ion. The laser-induced fluorescence spectra in Eu^<3+>-doped glasses and polymers have been compared with the experiments of the applied pressure in Eu^<3+>-doped crystals, and the effectiveness of the site-selective fluorescence method has been established. Less