Browsing by Author "Tsai, YL"

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Feasibility study of using refrigerant 1,1,1,2-tetrafluoroethane as the mobile phase in high-speed counter-current chromatography
(1999-03-12)
Tsai, YL
;
Yu, TI
;
應用化學系
;
Department of Applied Chemistry
Newly synthesized environmentally benign refrigerant 1,1,1,2-tetrafluoroethane (R134a) was used as the mobile phase in high-speed counter-current chromatography (HSCCC) in this study. R134a remains as a liquid under mild pressure and becomes a gas at atmospheric pressure. Accordingly, operation of HSCCC equipped with regular polytetrafluoroethylene tubing was satisfactory. Since R134a turned into gas at ambient temperature and pressure, further concentration for the collected fractions after elution was not required. A mixture of four standard components of Angelicae radix was separated to demonstrate the feasibility of using this new mobile phase in HSCCC. (C) 1999 Elsevier Science B.V. All rights reserved.
Photoluminescence of ZnSexTe1-x/ZnTe multiple-quantum-well structures grown by molecular-beam epitaxy
(2004-12-15)
Shih, YT
;
Tsai, YL
;
Yuan, CT
;
Chen, CY
;
Yang, CS
This work investigates photoluminescence (PL) spectra from ZnSexTe1-x/ZnTe multiple-quantum-well structures grown on GaAs(001) substrates by molecular-beam epitaxy. The PL data reveal that the band alignment of the ZnSexTe1-x/ZnTe system is type II. The thermal activation energy for quenching the PL intensity was determined from the temperature-dependent PL spectra. The activation energy was found to increase initially and then decrease as the thickness of the ZnSexTe1-x layers decreases from 7 to 3 nm. The temperature-dependent broadening of the PL linewidth was also investigated. The LO-phonon scattering was found to be the dominant broadening mechanism. (C) 2004 American Institute of Physics.