The clusters of Eu^3＋ ion in Eu（DBM）3Phen-doped polymethyl methacrylate （PMMA） have been studied by three means. The relative fluorescence intensity ratio of the ^5D0 → ^7F2 to ^5D0 → ^7F1 transitions with diff...The clusters of Eu^3＋ ion in Eu（DBM）3Phen-doped polymethyl methacrylate （PMMA） have been studied by three means. The relative fluorescence intensity ratio of the ^5D0 → ^7F2 to ^5D0 → ^7F1 transitions with different concentrations of Eu^3＋ in Eu（DBM）3Phen-doped PMMA and metastable-state （^5D0） lifetime dependence on Eu^3＋ concentration axe analyzed. The analysis indicates that there axe no clustering effects in Eu^3＋ ions of Eu（DBM）3Phen-doped PMMA when the Eu^3＋ doping concentration is up to 1.0 wt.-%. At the same time, the clustering effect has not been observed by the scanning neax-field optical microscopy （SNOM） in Eu（DBM）3Phen-doped PMMA with 1.0 wt.-% of Eu^3＋ ions. The analysis reveals that a high concentration of Eu^3＋ can be incorporated into polymer optical fiber （POF） without clustering effect.展开更多
This article summarizes work at the Laser Thermal Laboratory and discusses related studies on the laser synthesis and functionalization of semiconductor nanostructures and two-dimensional(2D)semiconductor materials.Re...This article summarizes work at the Laser Thermal Laboratory and discusses related studies on the laser synthesis and functionalization of semiconductor nanostructures and two-dimensional(2D)semiconductor materials.Research has been carried out on the laser-induced crystallization of thin films and nanostructures.The in situ transmission electron microscopy(TEM)monitoring of the crystallization of amorphous precursors in nanodomains is discussed herein.The directed assembly of silicon nanoparticles and the modulation of their optical properties by phase switching is presented.The vapor-liquid-solid mechanism has been adopted as a bottom-up approach in the synthesis of semiconducting nanowires(NWs).In contrast to furnace heating methods,laser irradiation offers high spatial selectivity and precise control of the heating mechanism in the time domain.These attributes enabled the investigation of NW nucleation and the early stage of nanostructure growth.Site-and shape-selective,on-demand direct integration of oriented NWs was accomplished.Growth of discrete silicon NWs with nanoscale location selectivity by employing near-field laser illumination is also reported herein.Tuning the properties of 2D transition metal dichalcogenides(TMDCs)by modulating the free carrier type,density,and composition can offer an exciting new pathway to various practical nanoscale electronics.In situ Raman probing of laser-induced processing of TMDC flakes was conducted in a TEM instrument.展开更多
Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by ...Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by the optical near field on the surface is measured as the electrostatic force. We demonstrated atomicresolution imaging of the near field on the α-Al2O3 （0001） surface of a prism. We investigated the spatial distribution of the near field by scanning at different tip-sample distances and found that the atomic corrugation of the near-field signal was observed at greater distances than that of the atomic force microscopy signal. As the tip-sample distance increased, the normalized signal-to-noise ratio of the near field is in a gradual decline almost twice that of the frequency shift （Δf）.展开更多
基金This work was supported by the National ScienceFoundation of China (No. 90201013), the Fujian NaturalScience Foundation of China (No. A0510014), and theFujian Educational Department Foundation of China(No. JB03151 and JB04246).
文摘The clusters of Eu^3＋ ion in Eu（DBM）3Phen-doped polymethyl methacrylate （PMMA） have been studied by three means. The relative fluorescence intensity ratio of the ^5D0 → ^7F2 to ^5D0 → ^7F1 transitions with different concentrations of Eu^3＋ in Eu（DBM）3Phen-doped PMMA and metastable-state （^5D0） lifetime dependence on Eu^3＋ concentration axe analyzed. The analysis indicates that there axe no clustering effects in Eu^3＋ ions of Eu（DBM）3Phen-doped PMMA when the Eu^3＋ doping concentration is up to 1.0 wt.-%. At the same time, the clustering effect has not been observed by the scanning neax-field optical microscopy （SNOM） in Eu（DBM）3Phen-doped PMMA with 1.0 wt.-% of Eu^3＋ ions. The analysis reveals that a high concentration of Eu^3＋ can be incorporated into polymer optical fiber （POF） without clustering effect.
基金The research was performed at the Laser Thermal Laboratory by Drs David J Hwang,Sang-gil Ryu,Eunpa Kim,Jung Bin In,and the current students,Letian Wang,Yoonsoo Rho and Matthew Eliceiri.Professors Andrew M Minor,Junqiao Wu,Oscar D Dubon,Drs Bin Xiang,Frances I Allen,and Changhyun Ko of UCB Materials Science and Engineering,and Dr Carlo Carraro of UCB Chem.Engineering contributed to the work.The research was supported by DARPA/MTO under TBN grant N66001-08-1-2041,the US Department of Energy SBIR grant(DE-FG02-07ER84813),Samsung GRO,and NSF CMMI-1363392.The in situ experiments were performed at the National Center for Electron Microscopy at the Lawrence Berkeley National Laboratory,which is supported by the Office of Science,Office of Basic Energy Sciences,Scientific User Facilities Division,of the US Department of Energy under Contract No.DE-AC02-05CH11231.The laser-induced nanowire growth and doping was conducted on the LACVD apparatus in the UC Berkeley Marvell Nanofabrication Laboratory.
文摘This article summarizes work at the Laser Thermal Laboratory and discusses related studies on the laser synthesis and functionalization of semiconductor nanostructures and two-dimensional(2D)semiconductor materials.Research has been carried out on the laser-induced crystallization of thin films and nanostructures.The in situ transmission electron microscopy(TEM)monitoring of the crystallization of amorphous precursors in nanodomains is discussed herein.The directed assembly of silicon nanoparticles and the modulation of their optical properties by phase switching is presented.The vapor-liquid-solid mechanism has been adopted as a bottom-up approach in the synthesis of semiconducting nanowires(NWs).In contrast to furnace heating methods,laser irradiation offers high spatial selectivity and precise control of the heating mechanism in the time domain.These attributes enabled the investigation of NW nucleation and the early stage of nanostructure growth.Site-and shape-selective,on-demand direct integration of oriented NWs was accomplished.Growth of discrete silicon NWs with nanoscale location selectivity by employing near-field laser illumination is also reported herein.Tuning the properties of 2D transition metal dichalcogenides(TMDCs)by modulating the free carrier type,density,and composition can offer an exciting new pathway to various practical nanoscale electronics.In situ Raman probing of laser-induced processing of TMDC flakes was conducted in a TEM instrument.
文摘Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by the optical near field on the surface is measured as the electrostatic force. We demonstrated atomicresolution imaging of the near field on the α-Al2O3 （0001） surface of a prism. We investigated the spatial distribution of the near field by scanning at different tip-sample distances and found that the atomic corrugation of the near-field signal was observed at greater distances than that of the atomic force microscopy signal. As the tip-sample distance increased, the normalized signal-to-noise ratio of the near field is in a gradual decline almost twice that of the frequency shift （Δf）.
