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显微光谱学研究发现CdTe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依赖于量子点的尺寸。还发现品质因数随着尺寸的减小而增加。利用SheikBahae的理论分析了非线性光学性质的尺寸依赖性。用时间分辨扫描探针显微镜对量子点合成的CdTe纳米线进行了分析，发现纳米线的异质性。此外，由于纳米线中的能量扩散，纳米线的激子湮灭比量子点增加。在先前的实验中，观察到由PVA和海藻糖包埋的单个QD的闪烁行为。我们发现，二氧化硅涂层的单量子点显着抑制闪烁，表明环境条件起着重要的作用，单量子点的发光性能。此外，CdS 关于我们 在低温下合成了纳米棒和量子点，并通过扫描探针显微镜（SPM）研究了它们的物理化学性质。2）银纳米棒的合成和表征在洗涤剂水溶液中，通过化学还原Ag ^+的种子介导生长方法制备了银纳米棒。在这种合成方法中，已经清楚地观察到等离子体吸收的纵向和横向模式。瞬态吸收动力学表明，振荡周期为20~40 ps的相干声振动是由纳米棒的放热引起的等离子体吸收带的周期性位移引起的。3）采用InGaAs光电二极管作为探测器，实现了高灵敏度的宽带瞬态吸收显微光谱探测，探测波长范围扩展到1.6 μ m，这使得我们能够以高灵敏度△ OD = 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 10 ^10 ^..<-7><-8>全局泵浦和局部探测几何结构也成功地用于瞬态吸收SNOM实验。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