Direct measurement of excitation energy relaxation processes in small domains by near field microspectroscopy

结合扫描近场显微镜和单光子计数技术，我们开发了皮秒时间分辨近场荧光显微光谱系统。同时满足100nm的空间分辨率、50ps的时间分辨率和nm的光谱分辨率，是目前国内最先进的系统，据我们所知只有少数实验室拥有类似的系统。该系统已应用于以下3种有机分子微晶体。1.研究了沉积的四烯微晶的荧光光谱与晶体厚度的关系，发现晶体厚度越薄，缺陷浓度越低，纯度越高。2.通过形貌测量和荧光光谱检测了蒽-四氯眼酸酐电荷转移微晶体的荧光不均匀性。从电子供体和受体分子的分离、供体-受体柱的取向、非发光缺陷的形成和杂质污染等方面讨论了与形貌相关或不相关的非荧光结构域。3.在-100 nm分辨率下，蒽-四氯眼酸酐和-焦美石酸酐混合CT微晶体显示纤维状结构，其取向各向异性和空间非均匀性被考虑。

By combining a scanning near field microscope and a single photon counting technique, we have developed a picosecond time-resolved near field fluorescence microspectroscopy system. Spatial resolution of 100 nm, temporal resolution of 50 ps, and spectral resolution of nm are simultaneously satisfeied, which is the most advanced system in our country and only a few laboratories have comparable systems as far as we know. The system has been applied to the following 3 organic molecular microcrystals. 1.Fluorescence spectra of deposited tetracene microcrystals were examined as a function of the crystal thickness of a few tens nm - submum, and it was found that the thinner is purer with the lower defect concentration. 2.fluorescence inhomogeneity of anthracene-tetrachlorophthalic anhydride charge transfer microcrystals were examined by measuring topography and fluorescence spectrum. Nonfluorescence domains, which are related or not related to topography, were discussed in terms of segregation of electron donor and acceptor molecules, orientation of donor-acceptor column, nonluminescent defect formation, and impurity contamination. 3.Mixed CT microcrystals of anthracene-tetrachlorophthalic anhydride and -pyromelitic anhydride show fiber-like structures whose orientation anisotropy and spatial inhomogeneity were considered with -100 nm resolution.