Browsing by Issue Date, starting with "2016-07-21"

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Stark Spectroscopy of Rubrene. II. Stark Fluorescence Spectroscopy and Fluorescence Quenching Induced by an External Electric Field
(2016-07-21)
Iimori, Toshifumi
;
Ito, Ryuichi
;
Ohta, Nobuhiro
;
應用化學系
;
應用化學系分子科學碩博班
We report Stark fluorescence spectroscopy investigation of rubrene dispersed in a poly(methyl methacrylate) film. The features of the fluorescence spectrum are analogous to those in solutions. In the Stark fluorescence spectrum, the decrease of the fluorescence quantum yield in the presence of an external electric field is observed. This result shows that the yield of nonradiative decay processes is increased by the application of an external electric field. It is known that the fluorescence quantum yield for rubrene, which is nearly unity at room temperature, depends on temperature, and a major nonradiative decay process in photoexcited rubrene is ascribed to a thermally activated intersystem crossing (ISC). Equations that express the field-induced fluorescence quenching in terms of the molecular parameters are derived from the ensemble average of electric field effects on the activation energy of the reaction rate constant in random orientation systems. The molecular parameters are then extracted from the observed data. It is inferred that the field-induced increase in the yield of other intramolecular and intermolecular photophysical processes in addition to the ISC should be taken into account.
Prominent role of oxygen in the multiferroicity of DyMnO3 and TbMnO3: A resonant soft x-ray scattering spectroscopy study
(2016-07-21)
Huang, S. W.
;
Lee, J. M.
;
Jeng, Horng-Tay
;
Shao, YuCheng
;
Wray, L. Andrew
Oxygen is known to play an important role in the multiferroicity of rare earth manganites; however, how this role changes with rare earth elements is still not fully understood. To address this question, we have used resonant soft x-ray scattering spectroscopy to study the F-type (0, tau, 0) diffraction peak from the antiferromagnetic order in DyMnO3 and TbMnO3. We focus on the measurements at O K edge of these two manganites, supplemented by the results at Mn L-2 and Dy M-5 edge of DyMnO3. We show that the electronic states of different elements are coupled more strongly in DyMnO3 than in TbMnO3, presumably due to the stronger lattice distortion and the tendency to develop E-type antiferromagnetism in the ferroelectric state that promote the orbital hybridization. We also show that the anomaly in the correlation length of (0, tau, 0) peak in DyMnO3 signifies the exchange interaction between Mn and rare earth spins. Our findings reveal the prominent role of oxygen orbitals in the multiferroicity of rare earth manganites and the distinct energetics between them.
Dual Strong Couplings Between TPPS J-Aggregates and Aluminum Plasmonic States
(2016-07-21)
Li, Jie
;
Ueno, Kosei
;
Uehara, Hiyori
;
Guo, Jingchun
;
Oshikiri, Tomoya
We report on the spectral properties of strong coupling between the localized surface plasmon resonances (LSPRs) of aluminum (Al) nanostructures and tetraphenylporphyrin tetrasulfonic acid hydrate (TPPS) J-aggregates. Because of their wide spectral range of LSPR bands from ultraviolet to near-infrared wavelengths by controlling structural size, Al nanodisks can realize strong coupling with different excitons of TPPS J-aggregates. The Rabi splitting energies of the excitons based on Soret and Qbands are 300 and 180 meV, respectively. In addition to extinction spectrum, we have also measured an excitation spectrum to determine the essential absorption of the hybrid states and successfully confirmed a shoulder peak corresponding to a lower branch of hybrid states. In Al nanorod systems, strong coupling with two excitons can also be selectively induced by merely rotating the polarization of the incident light, which constituted a simple platform for the dynamic control of exciton/plasmon coupling states.
Noninvasive, label-free, three-dimensional imaging of melanoma with confocal photothermal microscopy: Differentiate malignant melanoma from benign tumor tissue
(2016-07-22)
He, Jinping
;
Wang, Nan
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Tsurui, Hiromichi
;
Kato, Masashi
;
Iida, Machiko
Skin cancer is one of the most common cancers. Melanoma accounts for less than 2% of skin cancer cases but causes a large majority of skin cancer deaths. Early detection of malignant melanoma remains the key factor in saving lives. However, the melanoma diagnosis is still clinically challenging. Here, we developed a confocal photothermal microscope for noninvasive, label-free, three-dimensional imaging of melanoma. The axial resolution of confocal photothermal microscope is similar to 3 times higher than that of commonly used photothermal microscope. Three-dimensional microscopic distribution of melanin in pigmented lesions of mouse skin is obtained directly with this setup. Classic morphometric and fractal analysis of sixteen 3D images (eight for benign melanoma and eight for malignant) showed a capability of pathology of melanoma: melanin density and size become larger during the melanoma growth, and the melanin distribution also becomes more chaotic and unregulated. The results suggested new options for monitoring the melanoma growth and also for the melanoma diagnosis.
?水?理????
(2016-07-25)
黎 ?明
;
江明桂
;
陳金得
;
宋耿全
;
▲藍▼ ▲茜▼▲茹▼
【課題】?水?理?????提供??。【解決手段】本?明?係??水?理??????水中?少????一部分?化?的酸素要求量及?含窒素化合物?除去??、?炭素嫌?性流動床反?器及?窒素除去流動床反?器?備??。?炭素嫌?性流動床反?器?、主??水中?大部分?化?的酸素要求量?順?加水分解、酸化及????化????????、窒素除去流動床反?器則??水中??????態窒素及?余??化?的酸素要求量?部分的?硝化反?、?立?養性?硝反?及????養性?硝反????窒素??化???。【選??】?１
Biomimic nickel thiolate catalyst with CdS nanomaterial for photocatalytic hydrogen production in aqueous phase
(2016-07-25)
Gliniak, Jacek
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交大名義發表
;
National Chiao Tung University
Synergy of using neutralized DNA on nanowire field effect transistor as next generation biosensor
(2016-07-25)
Chen, Wen-Yih
;
Yang, Yuh-Shyong
;
Chan, Hardy W.
;
交大名義發表
;
National Chiao Tung University
Mobile-phone based visible light communication using region-grow light source tracking for unstable light source
(2016-07-25)
Liang, Kevin
;
Chow, Chi-Wai
;
Liu, Yang
;
光電工程學系
;
光電工程研究所
In order to increase the data rate of the camera-based visible light communication (VLC) system, using rolling shutter effect has been demonstrated successfully, in which the pixel rows of the complementary-metal-oxide-semiconductor (CMOS) image sensor are activated sequentially. Previous camera-based VLCs focused on using a stable LED light source, and its illumination area is positioned at the center of an image frame. In this work, we investigate the performance of a camera-based VLC with light source at different parts of an image frame. We propose and demonstrate using region-grow algorithm to track the light source. We also evaluate and discuss different scenarios when the light source is moved. Besides, a recorded > 5 kbit/s net data rate can be achieved by using only a single phosphor-based white-light LED source. Here, we demonstrate that 4.502 pixel/bit can be achieved. (C) 2016 Optical Society of America
(2016-07-25)
LEE DER-MING
;
CHIANG MING-KUEI
;
CHEN CHIN-TE
;
SUNG KENG-CHUAN
;
LAN CHIEN-JU
Enzymatic approach to configurationally rare trans-androsteronyl-alpha-glucoside and its potential for anticancer application
(2016-07-25)
Wu, Tung-Kung
;
交大名義發表
;
National Chiao Tung University
Enzymatic approach to configurationally rare trans-androsteronyl-alpha-glucoside and its potential for anticancer application
(2016-07-25)
Wu, Tung-Kung
;
交大名義發表
;
National Chiao Tung University
Electrically tunable transmission of gold binary-grating metasurfaces integrated with liquid crystals
(2016-07-25)
Chen, Kuo-Ping
;
Ye, Shi-Cheng
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Yang, Chi-Yin
;
Yang, Zong-Han
;
Lee, Wei
Planar photonics using metasurfaces is of great interest because a metasurface can control the flow of light beyond that attainable with natural materials. The resonance wavelength of a binary-grating metasurface is adjustable by changing the width and thickness of the nanostructure. We propose a novel combination of nematic liquid crystals and a binary-grating metasurface with which the diffraction efficiency can be controlled by adjusting the applied voltage. (C) 2016 Optical Society of America
Synergy of using neutralized DNA on nanowire field effect transistor as next generation biosensor
(2016-07-25)
Chen, Wen-Yih
;
Yang, Yuh-Shyong
;
Chan, Hardy W.
;
交大名義發表
;
National Chiao Tung University
Biomimic nickel thiolate catalyst with CdS nanomaterial for photocatalytic hydrogen production in aqueous phase
(2016-07-25)
Gliniak, Jacek
;
交大名義發表
;
National Chiao Tung University
Dynamics of phonons in Sr3Ir4Sn13: an experimental study by ultrafast spectroscopy measurements
(2016-07-26)
Luo, C. W.
;
Cheng, P. C.
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Tu, C. M.
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Kuo, C. N.
;
Wang, C. M.
We report a study of ultrafast dynamics of photoexcited electrons and phonons in Sr3Ir4Sn13 using dual-color transient reflectivity change (Delta R/R) measurements. Time resolved optical spectroscopy of collective excitations reveal the marked features near its structural phase transition temperature T* similar or equal to 147 K. Two distinctive oscillatory timescales in Delta R/R have been clearly resolved. The rapid THz-range oscillations are attributed to the dynamics of the optical phonons which strongly correlate to the structural phase transition. The slow GHz-range oscillatory phenomenon which only occurs below about 150 K is associated with the dynamic response of the longitudinal-acoustic phonons. These low-energy phonons show a softening feature on approaching the transition temperature, also indicating a strong relevance to the structural phase transition. The information that we demonstrated would provide a deeper understanding of the structural phase transition in Sr3Ir4Sn13.
Synthesis of a 4,9-Didodecyl Angular-Shaped Naphthodiselenophene Building Block To Achieve High-Mobility Transistors
(2016-07-26)
Tsai, Che-En
;
Yu, Ruo-Han
;
Lin, Fang-Ju
;
Lai, Yu-Ying
;
Hsu, Jhih-Yang
A new tetracyclic 4,9-dialkyl angular-shaped naphthodiselenophene (4,9-alpha-aNDS) was designed and synthesized. The naphthalene core in 4,9-alpha-aNDS is formed by the DBU-induced 6 pi-cyclization of an (E)-1,2-bis(3-(tetradec-1-yn-1-yl)selenophen-2-yl)ethene intermediate followed by the second PtCl2-catalyzed benzannulation. This synthetic protocol allows for incorporating two dodecyl groups regiospecifically at 4,9-positions of the resulting alpha-aNDS. An ordered supramolecular self-assembly formed via noncovalent selenium-selenium interactions with a short contact of 3.5 angstrom was observed in the single-crystal structure of 4,9-alpha-aNDS. The distannylated alpha-aNDS building block was copolymerized with Br-DTFBT and Br-DPP acceptors by Stille cross coupling to form two new donor-acceptor polymers P alpha NDSDTFBT and P alpha NDSDPP, respectively. The bottom-gate/top-contact organic field-effect devices using the PaNDSDTFBT and PaNDSDPP semiconductors accomplished superior hole mobility of 3.77 and 2.17 cm(2) V-1 s(-1), respectively, which are among the highest mobilities reported to date.
Electrochemical and in situ X-ray spectroscopic studies of MnO2/reduced graphene oxide nanocomposites as a supercapacitor
(2016-07-28)
Chang, Han-Wei
;
Lu, Ying-Rui
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Chen, Jeng-Lung
;
Chen, Chi-Liang
;
Lee, Jyh-Fu
Electrochemical and in situ X-ray absorption spectroscopy (XAS) measurements of various MnO2-coated carbon materials (MnO2/acid-functionalized carbon nanotubes (C-CNT), MnO2/reduced graphene oxide (RGO), and MnO2/RGO-Au electrodes) were conducted to evaluate the supercapacitive performances and electronic structures. MnO2 was deposited on the surface of C-CNT, RGO, and RGO-Au via a spontaneous redox reaction to facilitate the growth of the bulk form of MnO2/C-CNT and the surface forms of MnO2/RGO-based materials. Various forms of MnO2 on the carbon materials exhibited different charge/discharge behaviors. The specific capacitances of the MnO2/RGO and MnO2/RGO-Au electrodes at a current density of 1 A g(-1) were about 433 and 469 F g(-1), respectively; these values are about 1.5 times that of the MnO2/C-CNT (259 F g(-1)) electrode. Specific capacitances of 220 and 281 F g(-1) with retention rates of about 50-60% were obtained from MnO2/RGO and MnO2/RGO-Au, respectively, even at a high current density of 80 A g(-1). Experimental results revealed that the long-term electrochemical stability of the MnO2/RGO-based electrodes (with similar to 90% retention) exceeded that of the MnO2/C-CNT electrode (with similar to 60% retention) after 1000 cycles at a high scan rate of 80 A g(-1). This finding indicates that MnO2/RGO-based electrodes feature excellent cycling stability and rate capacity retention performance. To elucidate the atomic/electronic structures of the MnO2/C-CNT, MnO2/RGO, and MnO2/RGO-Au electrodes during the charge/discharge process, in situ XAS of the Mn K-edge was performed. The MnO2/RGO-based electrodes exhibited the least variations in the pre-peak intensity of the Mn K-edge during the charge/discharge process because a nano-network of MnO2 is homogeneously decorated on the outer surfaces of RGO-based electrodes to facilitate the growth of surface forms of MnO2/RGO and MnO2/RGO-Au. Analytical results further revealed suppression of changes in tunnel size and promotion of insertion/extraction behavior. This work, particularly the combination of cyclic voltammetry with in situ XAS measurements, will be of general value in the fields of nanomaterials and nanotechnology, and in their use in energy storage.
Substrate-induced structures of bismuth adsorption on graphene: a first principles study
(2016-07-28)
Lin, Shih-Yang
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Chang, Shen-Lin
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Chen, Hsin-Hsien
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Su, Shu-Hsuan
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Huang, Jung-Chun
The geometric and electronic properties of Bi-adsorbed monolayer graphene, enriched by the strong effect of a substrate, are investigated by first-principles calculations. The six-layered substrate, corrugated buffer layer, and slightly deformed monolayer graphene are all simulated. Adatom arrangements are thoroughly studied by analyzing the ground-state energies, bismuth adsorption energies, and Bi-Bi interaction energies of different adatom heights, inter-adatom distance, adsorption sites, and hexagonal positions. A hexagonal array of Bi atoms is dominated by the interactions between the buffer layer and the monolayer graphene. An increase in temperature can overcome a similar to 50 meV energy barrier and induce triangular and rectangular nanoclusters. The most stable and metastable structures agree with the scanning tunneling microscopy measurements. The density of states exhibits a finite value at the Fermi level, a dip at similar to -0.2 eV, and a peak at similar to-0.6 eV, as observed in the experimental measurements of the tunneling conductance.
Reflection Microspectroscopic Study of Laser Trapping Assembling of Polystyrene Nanoparticles at Air/Solution Interface
(2016-07-28)
Wang, Shun-Fa
;
Yuyama, Ken-ichi
;
Sugiyama, Teruki
;
Masuhara, Hiroshi
;
應用化學系
We present the formation of a single nanoparticle assembly with periodic array structure induced by laser trapping of 200 nm polystyrene nanoparticles at air/solution interface of the colloidal heavy water solution. Their trapping and assembling behavior is observed by monitoring transmission and backscattering images and measuring reflection spectra under a microscope. Upon the laser irradiation into the solution surface layer, nanoparticles are gathered at and around the focal spot, and eventually a nanoparticle assembly with the size much larger than the focal volume is formed. The assembly gives structural color in visible range under halogen lamp illumination, indicating that constituent nanoparticles are periodically arrayed. Reflection spectra of the assembly show a reflection band, and its peak position is gradually shifted to short wavelength and the bandwidth becomes narrow with time, depending on the distance from the focal spot. After the laser is switched off, red-shift is observed in the reflection band. These results indicate that nanoparticles are rearranged into a densely packed periodic array during laser irradiation and diffused out to the surrounding solution after turning off the laser. These dynamics are discussed from the viewpoints of the attractive optical trapping force and the electrostatic repulsive force among nanoparticles.
Infrared absorption spectrum of the simplest deuterated Criegee intermediate CD2OO
(2016-07-28)
Huang, Yu-Hsuan
;
Nishimura, Yoshifumi
;
Witek, Henryk A.
;
Lee, Yuan-Pern
;
應用化學系
We report a transient infrared (IR) absorption spectrum of the simplest deuterated Criegee intermediate CD2OO recorded using a step-scan Fourier-transform spectrometer coupled with a multipass absorption cell. CD2OO was produced from photolysis of flowing mixtures of CD2I2, N-2, and O-2 (13 or 87 Torr) with laser light at 308 nm. The recorded spectrum shows close structural similarity with the spectrum of CH2OO reported previously [Y.-T. Su et al., Science 340, 174 (2013)]. The four bands observed at 852, 1017, 1054, and 1318 cm(-1) are assigned to the OO stretching mode, two distinct in-plane OCD bending modes, and the CO stretching mode of CD2OO, respectively, according to vibrational wavenumbers, IR intensities, rotational contours, and deuterium-isotopic shifts predicted with extensive quantum-chemical calculations. The CO-stretching mode of CD2OO at 1318 cm(-1) is blue shifted from the corresponding band of CH2OO at 1286 cm(-1); this can be explained by a mechanism based on mode mixing and isotope substitution. A band near 936 cm(-1), observed only at higher pressure (87 Torr), is tentatively assigned to the CD2 wagging mode of CD2IOO. Published by AIP Publishing.