Browsing by Author "Luo, Li-Yang"

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BIOT 373-Artificial myoglobin system design for electron transfer mechanism study and BioSolar cell applications
(2006-09-10)
Chang, Chin-Hao
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Wu, Tung-Kung
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Diau, Eric Wei Guang
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Luo, Li-Yang
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生物科技學系
Fluorescence dynamics of zinc protoporphyrin in solution and inside anodized aluminum oxide (AAO) nano-channel arrays
(2006-12-01)
Lin, Jin-Shyong
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Chen, Yu-Chying
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Chen, Chien-Chon
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Luo, Li-Yang
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Diau, Eric Wei-Guang
The excited-state relaxation dynamics of zinc protoporphyrin (ZnPP) in THF solution and inside nano-channel arrays of anodized aluminum oxide (AAO) have been investigated with time-correlated single-photon-counting (TCSPC) fluorescence spectra with S-2 excitation (lambda(ex) = 435 nm). We used three initial concentrations of immersion - 4.8 x 10(-6), 4.8 x 10(-5) and 4.8 x 10(-4) M - to examine the extent of aggregation of ZnPP inside the AAO nano-channel arrays of two pore sizes - 15 and 70 nm. Only one decay component corresponds to the aggregation of ZnPP in THF solution, whereas at least two decay components are required to describe the transient behavior of ZnPP inside AAO. The observed systematic variation of the decay coefficients and the corresponding amplitudes of the ZnPP/AAO samples are consistent with the observation of steady-state spectra of the system reported previously (JCCS 2006, 53, 201), but through fluorescence lifetime measurements we further highlight the significance of aggregation of ZnPP in the specific nanoporous environment that is not achievable in ZnPP/THF solutions in large concentrations.
Highly selective fluorescent sensing of Cu(2+) ion by an arylisoxazole modified calix[4]arene
(2008-08-18)
Chang, Kai-Chi
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Luo, Li-Yang
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Diau, Eric Wei-Guang
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Chung, Wen-Sheng
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應用化學系
A novel fluorescent chemosensor 1 with two anthraceneisoxazolymethyl groups at the lower rim of calix[4]arene has been synthesized, which revealed a dual emission (monomer and excimer) when excited at 375 nm. This chemosensor displayed a selective fluorescence quenching only with Cu(2+) ion over all other metal ions examined. When Cu(2+) ion was bound to 1, the fluorescence intensities of both monomer and excimer were quenched. Furthermore, the association constant for the 1:1 complex of 1.Cu(2+) was determined to be (1.58 +/- 0.03) x 10(4) M(-1). (c) 2008 Elsevier Ltd. All rights reserved.
Investigation of Pr(3+) as a sensitizer in quantum-cutting fluoride phosphors
(2008-02-25)
Lee, Te-Ju
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Luo, Li-Yang
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Cheng, Bing-Ming
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Diau, Wei-Guang
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Chen, Teng-Ming
A quantum-cutting (QC) phosphor K(2)GdF(5):Eu(3+) shows poor optical absorption and a theoretical quantum efficiency (QE) of 107% in the ultraviolet (UV) and vacuum ultraviolet (VUV) excitation spectral ranges. Pr(3+) was codoped as a sensitizer in K(2)GdF(5): Eu(3+) thus increasing the absorption in the UV and VUV spectral regions; the theoretical QE of K(2)GdF(5): Eu(3+), Pr(3+) was increased to 138%. The spectra indicate that the possible mechanisms of QC and energy transfer differ from those of phosphors containing the Gd(3+) -Eu(3+) couple. Temporally resolved measurements of fluorescence decay confirm the proposed QC mechanism for the phosphor containing the Gd(3+) -Eu(3+),Pr(3+) system. (C) 2008 American Institute of Physics.
m-Benziporphodimethene: a new porphyrin analogue fluorescence zinc(II) sensor
(2008)
Hung, Chen-Hsiung
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Chang, Gao-Fong
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Kumar, Anil
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Lin, Geng-Fong
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Luo, Li-Yang
m-Benziporphodimethene is presented here as a long-wavelength Zn2+ specific chemosensor; this sensor shows fluorescence switch-on upon Zn2+ binding with no apparent background fluorescence.
Visible quantum cutting through downconversion in green-emitting K2GdF5 : Tb3+ phosphors
(2006-09-25)
Lee, Te-Ju
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Luo, Li-Yang
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Diau, Eric Wei-Guang
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Chen, Teng-Ming
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Cheng, Bing-Ming
Visible quantum cutting under excitations at 212 and 172 nm in a green-emitting phosphor K2GdF5:Tb3+ (11%) via a downconversion mechanism is investigated. The authors measured the vacuum ultraviolet (VUV) excitation and emission spectra and proposed mechanisms to rationalize the quantum-cutting effect. One short-UV or one VUV photon absorbed by Tb3+ is split into multiple visible photons emitted by Tb3+ through cross relaxation and direct energy transfer. Calculations indicate an optimal quantum efficiency as great as 189% for this phosphor. (c) 2006 American Institute of Physics.