Time-resolved near-field spectroscopic study on photophysical processes at solid/liquid interface

1)半导体纳米结构的扫描探针光谱性质研究发现，量子点的双光子吸收截面和非线性折射率等非线性光学性质强烈地依赖于量子点的尺寸。研究还发现，优值系数也随着尺寸的减小而增加。用Sheik Bahae的理论分析了非线性光学性质与尺寸的关系。用时间分辨扫描电子显微镜对由量子点合成的CdTe纳米线进行了分析，表明了纳米线的异质性。此外，由于纳米线中的能量扩散，与量子点相比，纳米线的激子湮没增加。在以前的实验中，观察到了PVA和海藻糖包埋的单个量子点的闪烁行为。我们发现，单个CdTe量子点的二氧化硅涂层显著抑制了闪烁，这表明环境条件对单个量子点的发光特性起着重要的作用。此外，CDS…在低温下合成了较多的纳米棒和量子点，并用扫描电子显微镜对它们的物理化学性质进行了测试。2)银纳米棒的合成与表征采用晶种介导法，在洗涤剂水溶液中用化学还原法制备了银纳米棒。在这种合成方法中，可以清楚地观察到等离子体吸收的纵模和横模。暂态吸收动力学表明，振荡周期为20~40ps的相干声振动源于纳米棒的热释放，引起等离子体吸收带的周期性移动。3)采用InGaAs光二极管作为探测器，将高灵敏度的宽带暂态吸收显微光谱探测波长范围扩大到1.6mInGaAs光二极管，这使得我们能够在高灵敏度的OD=10μ；-7；-8&gT；的高灵敏度界面上研究激子离域动力学或弱分子间相互作用动力学。较少

1) Spectroscopic Properties of Semiconductor Nanostructures by Scanning Probe Microspectroscopy Non-linear optical properties such as two-photon absorption cross section and nonlinear refractive index of CdTe QDs were found to strongly depend on a size of QDs. The figure of merit was also found to increase with decreasing the size. The size dependence of nonlinear optical properties was analyzed by the theory derived by Sheik Bahae. CdTe nanowires synthesized from QDs was analyzed by time-resolved SPM, suggesting the heterogeneity of nanowires. In addition, the exciton annihilation of nanowires increased as compared with QDs because of the energy diffusion in nanowires. In previous experiments, blinking behavior was observed for single QD embedded by PVA and trehalose. We have found that the silica coating of a single CdTe QD dramatically suppress the blinking, suggesting that the environmental condition plays an important role for luminescence properties of single QD. Furthermore, CdS … More e nanorods and QDs were synthesized at low temperature and their physicochemical properties have been examined by SPM.2) Synthesis and Characterization of Ag Nanorods Silver nanorods were prepared by a seed-mediated growth approach with chemical reduction of Ag^+ in a detergent aqueous solution. Longitudinal and transverse modes of plasmon absorption have been clearly observed in this synthetic approach. Transient absorption dynamics indicates that the coherent acoustic vibration with oscillation period of 20 to 40 ps was originated from the heat release of nanorods that induces a periodic shift of plasmon absorption bands. By the analysis of acoustic vibration, the size of synthetic nanorods and the aspect ratio have been estimated.3) Highly-sensitive, Broadband Transient Absorption Microspectroscopy Detection wavelength region was expanded up to 1.6 μm by using InGaAs photodiode as a detector, which enables us to examine the dynamics of exciton delocalization or weak intermolecular interaction dynamics in small domains at interface with high sensitivity of △OD = 10^<-7> 〜 10^<-8>..Global-pump and local-probe geometry was also successful for transient absorption SNOM experiments. Less