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Development of Optical Resonance Dynamic Spectroscopy for Single Microparticles

单微粒光学共振动态光谱学的发展

基本信息

批准号：
10305007
负责人：
SASAKI Keiji
金额：
$ 18.24万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

Microparticles, such as organic microcrystals, semiconductor powders, metallic beads, and liquid droplets, possess characteristic physical and chemical properties different from bulk materials. Although various kinds of spectroscopic techniques have been applied for elucidating reaction processes occurring in/on microparticles, these studies were performed by conventional time-resolved but space-unresolved spectroscopy so that the experimental results provided information on the sum of many particles with different properties. Behaviors of individual microparticles are expected to be different from each other depending on the sizes and shapes. In this research, we propose a new dynamics spectroscopy method for analyzing the photophysical and photochemical phenomena of a single microparticle with high accuracy and high sensitivity. This method is based on the optical resonance within the microsphere. Compared with the absorption loss caused by a single path through the particle, the change in the emission intensity was extremely amplified by the optical resonance in a spherical microparticle. Namely, the intracavity absorption spectroscopy is realized for the analysis of excited molecules in a microparticle. In addition, since a micrometer-sized short cavity has the ability to produce a picosecond lasing pulse with a single shot pumping, the ultrafast transient absorption process in the particle can be measured based on the pump-probe method. We succeeded in observing enhancement of spontaneous emission within polymer microspheres compared to that in free space, i.e., cavity quantum electrodynamic effect. Fluorescence decay rate increased with reducing the particle size, and the enhancement factor was determined to be -17 for a 2.4-μm latex sphere. The microspherical cavity enhancement of energy transfer processes caused by dipole-dipole interactions was also observed for aromatic-molecules-doped polymer microspheres.

微粒子，如有机微晶、半导体粉末、金属珠和液滴，具有不同于块状材料的特征物理和化学性质。虽然各种各样的光谱技术已被应用于阐明发生在/微粒上的反应过程，这些研究是由传统的时间分辨，但空间分辨光谱，使实验结果提供了信息的总和，许多粒子具有不同的属性。预期各个微粒的行为取决于尺寸和形状而彼此不同。在本研究中，我们提出了一种新的动力学光谱方法，用于分析单个微粒的物理和光化学现象，具有高精度和高灵敏度。该方法基于微球内的光学共振。与通过颗粒的单一路径引起的吸收损耗相比，发射强度的变化被球形微粒中的光学共振极大地放大。即，实现了用于分析微粒中的激发分子的腔内吸收光谱。此外，由于微米尺寸的短腔具有单次泵浦产生皮秒激光脉冲的能力，因此可以基于泵浦-探测方法测量粒子中的超快瞬态吸收过程。我们成功地观察到聚合物微球内的自发辐射比自由空间中的自发辐射增强，即，腔量子电动力学效应荧光衰减率随粒径的减小而增大，对粒径为2.4 μm的乳胶球，荧光增强因子为-17。芳香族分子掺杂聚合物微球中偶极-偶极相互作用引起的能量传递过程的微球空腔增强也被观察到。