Browsing by Author "Huang, Jane"

Now showing 1 - 4 of 4

Blinking Suppression and Anti-Bunching of Quantum Dots as Single-Photon Sources
(2010-01-01)
Yu, Pyng
;
Yuan, Chi-Tsu
;
Ko, Hsien-Chien
;
Huang, Jane
;
Tang, Jau
We report here our study on suppression of fluorescence blinking of colloidal CdSe/ZnS quantum dots (QDs) for potential applications as high performance single-photon sources. Blinking is an interesting property for single QDs, but it is undesirable for their applications. We have demonstrated that by coupling these QDs to adjacent silver nanoprisms, we could not only completely suppress the blinking but also enhance the fluorescence quantum yield, and also increase the fluorescence decay rates. These single QDs also exhibit anti-bunching behavior which is a signature for a single-photon emitter. In addition, we have also achieved blinking suppression by embedded the QDs in agarose gel. The electrostatic environment around QDs due to negatively charged fibers of gel might strongly affect the extent of blinking suppression. The mechanisms of blinking suppression will be discussed in the frame work of diffusion-controlled electron transfer model.
Environmental effects on photoinduced electron transfer and fluorescence blinking of single semiconducting nanocrystals in various matrices
(2010-01-01)
Ko, H. C.
;
Yuan, C. T.
;
Yu, Ping
;
Huang, Jane
;
Tang, Jau
In this report we explore how the surrounding environments around a single semiconducting nancrystal affect the photoinduced electron transfer, charge trapping fluorescence lifetime and fluorescence blinking. Using the time-correlated single photon counting techniques combined with confocal microscopy, we investigated photoluminescence of single CdSe/ZnS quantum dots embedded in agarose gel and on conductive substrates as examples. Understanding of the underlying mechanisms would allow us to better control of the photoluminescence properties of nanoparticles and to improve their performance in biophotonics and optoelectronics applications such as fluorescence markers, single-photon sources, photovoltaics and quantum dot lasers.
Selective acoustic phonon mode excitation of multi-mode silver nanoprisms
(2010-08-30)
Tai, Po-Tse
;
Yu, Pyng
;
Huang, Jane
;
Tang, Jau
;
光電工程學系
Nanoprisms are known to exhibit two major planar phonon modes in ultrafast experiments, namely, a stronger mode related to the bisector height and a weaker mode related to half of the edge length. In this work we demonstrated photoacoustic excitation of a specific acoustic phonon mode in silver nanoprisms using two properly timed pump pulses. Using this technique, we could selectively excite only the weak totally symmetric mode while suppressing the dominant breathing mode. Via direct observation of such a mode, which is hardly detectable directly with the conventional single pump pulse technique, we could elucidate the roles of hot electrons in photoinduced ultrafast structural dynamics in laser-heated nanoparticles. (C) 2010 Elsevier B.V. All rights reserved.
Synthesis of Silver Nanoprisms and Nanodiscs an Applications in Fluorescence Blinking Suppression
(2010)
Yu, Pyng
;
Huang, Jane
;
Yuan, Chi-Tsu
;
Tang, Jan
;
光電工程學系
In this work we investigated the influence of reagents in the synthesis of triangular silver nanoprisms through direct chemical reduction. We identified the chemical role of each reagent, i e H(2)O(2), poly(vinylpyrrolidone) (PVP) and NaBH(4), by systematically varying one reagent concentration while keeping the concentration of other reagents constant We also discuss the applications of nanoprisms in blinking suppression of single semiconductor quantum dots. In addition, we also investigated the synthesis of silver nanodiscs through the reconstruction of triangular nanoprisms using halide ions. The results from different halide ions presented the different face-selective etching rates on the well-identified facet in the silver nanoprism.