Develoment of a Ultra-Minute Laser Scanning Microscope and Novel Optical Properties

我们研制了一台基本共焦型的超微简易扫描激光显微镜，它工作在低温下，效率高，分辨率高，不需要费力的调整。适当长度的梯度折射率棒型微透镜可以作为无工作距离的物镜工作，因为通过棒透镜一侧的入射平行光束聚焦在另一侧平面上。由于固体浸没透镜(Sil)效应，这种棒状透镜提高了显微镜的分辨率，并有效地收集了直接附着在焦平面上的样品发出的荧光。这就是为什么我们提出了梯度折射率固体浸没透镜扫描显微镜(GRIN-SBL显微镜)来研究凝聚态物质的光学性质。另一方面，超越这一…的近场扫描光学显微镜原则上，More Limit必须在很低的信号强度下工作，没有得到充分的实际应用。我们研制的GRIN-SBL显微镜填补了这些不足，并被证明是非常有用的特定用途。在1.6K下，我们在十二烷晶体中的单分子涤纶上和在聚乙烯硫酸酯薄膜中的卤化假异氰胺分子J聚集体上展示了性能。在后一种体系中，由于准一维Frenkel激子的形成，尖锐而强烈的J带的光谱特征从单体的光谱特征向红移最为显著，但与其微观结构的关系尚不清楚。为了深入了解这一问题，我们尝试观察了PVS聚合物薄膜中J-聚集体纤丝状结构的局部反射光谱，并结合微观形态观察给出了初步的结果，提出了激子-极化模型。我们还开始了用合成化学方法制备有机-无机纳米复合半导体CdSe纳米晶，其光学性质用准零维Wannier激子表征。为了改善CdSe纳米晶的光学性能，采用宽禁带材料硫化锌进行钝化处理。虽然纳米晶的尺寸被限制在2~5 nm的范围内，但仍获得了大于50%的荧光量子效率。较少

We have developed an ultra-minute simple scanning laser microscope which is of basically confocal type and operates at cryogenic temperature with high efficiency and resolution without laborious adjustment. A gradient index rod-type micro lens with suitable length can operate as an objective lens with no working distance because an incident parallel beam passed through one side of the rod lens focuses on the other side plane. Due to the solid immersion lens (SIL) effect, this rod lens enhances the resolution of microscope and also collect efficiently the fluorescence emitted by a sample directly attached on the focal plane. This is the reason why we proposed the gradient index solid immersion lens scanning microscope (grin-SBL microscope) for the study of optical properties of condensed matter.In spite of high efficiency, traditional optical microscope has a limit of resolution due to the diffraction of light. On the other side, near field scanning optical microscope(NSOM) beyond this … More limit in principle must operate instead at very low signal intensities and has not been put into practical use sufficiently. The grin-SBL microscope we have developed here fills up these deficiencies and proved to be very useful for specified purposes.The performance was demonstrated on single molecules of terrylene in a dodecane crystal at 1.6 K and on molecular J aggregates by halogenated pseudoisocyanine in poly (vinylsulfate) thin film. In the latter system, while spectral characteristics of sharp and intense J-band shifted to the red from that of the monomers due to the formation of quasi-1D Frenkel exciton is most notable, a relation to its microscopic structures is not clear yet. To get insight into this issue, we have tried to observe local reflection spectra of the J-aggregates fibril-shape structures provided in thin PVS polymer films, preliminary results of which is presented in connection with their microscopic morphological observations and exciton-polariton model is proposed.We have also started a preparation of organic-inorganic nano-composite nanocrystals of semiconductor CdSe with synthetic chemical ways, whose optical properties are characterized with quasi zero dimensional Wannier excitons. To improve optical properties of CdSe nanocrystals, passivation with a wider gap material ZnS was performed. Although the nanocrystal sizes are limited to the range of 2〜5nm in diameter, the quantum efficiency of fluorescence greater than 50% is obtained. Less