Browsing by Issue Date, starting with "2011-11-04"

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Laser-Induced Crystallization and Crystal Growth
(2011-11-04)
Sugiyama, Teruki
;
Masuhara, Hiroshi
;
應用化學系
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應用化學系分子科學碩博班
;
Department of Applied Chemistry
Recent streams of laser studies on crystallization and crystal growth are summarized and reviewed. Femtosecond multiphoton excitation of solutions leads to their ablation at the focal point, inducing local bubble formation, shockwave propagation, and convection flow. This phenomenon, called "laser micro tsunami" makes it possible to trigger crystallization of molecules and proteins from their supersaturated solutions. Femtosecond laser ablation of a urea crystal in solution triggers the additional growth of a single daughter crystal. Intense continuous wave (CW) near infrared laser irradiation at the air/solution interface of heavy-water amino acid solutions results in trapping of the clusters and evolves to crystallization. A single crystal is always prepared in a spatially and temporally controlled manner, and the crystal polymorph of glycine depends on laser power, polarization, and solution concentration. Upon irradiation at the glass/solution interface, a millimeter-sized droplet is formed, and a single crystal is formed by shifting the irradiation position to the surface. Directional and selective crystal growth is also possible with laser trapping. Finally, characteristics of laser-induced crystallization and crystal growth are summarized.
Photodissociation Dynamics of Benzaldehyde (C(6)H(5)CHO) at 266, 248, and 193 nm
(2011-11-04)
Bagchi, Arnab
;
Huang, Yu-Hsuan
;
Xu, Z. F.
;
Raghunath, P.
;
Lee, Yuan T.
The photodissociation of gaseous benzaldehyde (C(6)H(5)CHO) at 193, 248, and 266 nm using multimass ion imaging and step-scan time-resolved Fourier-transform infrared emission techniques is investigated. We also characterize the potential energies with the CCSD(T)/6-311+G(3df,2p) method and predict the branching ratios for various channels of dissociation. Upon photolysis at 248 and 266 nm, two major channels for formation of HCO and CO, with relative branching of 0.37:0.63 and 0.20:0.80, respectively, are observed. The C(6)H(5)+HCO channel has two components with large and small recoil velocities; the rapid component with average translational energy of approximately 25 kJ mol(-1) dominates. The C(6)H(6)+CO channel has a similar distribution of translational energy for these two components. IR emission from internally excited C(6)H(5)CHO, nu(3) (nu = 1) of HCO, and levels nu <= 2, J <= 43 of CO are observed; the latter has an average rotational energy of approximately 13 kJ mol(-1) and vibrational energy of approximately 6 kJ mol(-1). Upon photolysis at 193 nm, similar distributions of energy are observed, except that the C(6)H(5)+HCO channel becomes the only major channel with a branching ratio of 0.82 +/- 0.10 and an increased proportion of the slow component; IR emission from levels nu(1) (nu = 1) and nu(3) (nu = 1 and 2) of HCO and nu <= 2, J <= 43 of CO are observed; the latter has an average energy similar to that observed in photolysis at 248 nm. The observed product yields at different dissociation energies are compared to statistical-theory predicted results based on the computed singlet and triplet potential-energy surfaces.
Photolysis Cross-Section of Ozone Dimer
(2011-11-04)
Chen, I-Cheng
;
Chen, Andrew F.
;
Huang, Wen-Tsung
;
Takahashi, Kaito
;
Lin, Jim J.
The Role of the n pi* (1)A(u) State in the Photoabsorption and Relaxation of Pyrazine
(2011-11-04)
Lin, Chih-Kai
;
Niu, Yingli
;
Zhu, Chaoyuan
;
Shuai, Zhigang
;
Lin, Sheng Hsien
The geometric, energetic, and spectroscopic properties of the ground state and the lowest four singlet excited states of pyrazine have been studied by using DFT/TD-DFT, CASSCF, CASPT2, and related quantum chemical calculations. The second singlet n pi* state, (1)A(u), which is conventionally regarded dark due to the dipole-forbidden (1)A(u) <- (1)A(g) transition, has been investigated in detail. Our new simulation has shown that the state could be visible in the absorption spectrum by intensity borrowing from neighboring n pi* (1)B(3u) and pi pi* (1)B(2u) states through vibronic coupling. The scans on potential-energy surfaces further indicated that the (1)A(u) state intersects with the (1)B(2u) states near the equilibrium of the latter, thus implying its participation in the ultrafast relaxation process.
Porphyrin-Sensitized Solar Cells with Cobalt (II/III)-Based Redox Electrolyte Exceed 12 Percent Efficiency
(2011-11-04)
Yella, Aswani
;
Lee, Hsuan-Wei
;
Tsao, Hoi Nok
;
Yi, Chenyi
;
Chandiran, Aravind Kumar
The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co((II/III))tris(bipyridyl)-based redox electrolyte in conjunction with a custom synthesized donor-pi-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency of 12.3% under simulated air mass 1.5 global sunlight.
Photodissociation Dynamics of Benzaldehyde (C6H5CHO) at 266, 248, and 193 nm
(2011-11-04)
Bagchi, Arnab
;
Huang, Yu-Hsuan
;
Xu, Z. F.
;
Raghunath, P.
;
Lee, Yuan T.
The photodissociation of gaseous benzaldehyde (C6H5CHO) at 193, 248, and 266 nm using multimass ion imaging and step-scan time-resolved Fourier-transform infrared emission techniques is investigated. We also characterize the potential energies with the CCSD(T)/6-311+G(3df,2p) method and predict the branching ratios for various channels of dissociation. Upon photolysis at 248 and 266 nm, two major channels for formation of HCO and CO, with relative branching of 0.37:0.63 and 0.20:0.80, respectively, are observed. The C6H5+HCO channel has two components with large and small recoil velocities; the rapid component with average translational energy of approximately 25 kJ mol(-1) dominates. The C6H6+CO channel has a similar distribution of translational energy for these two components. IR emission from internally excited C6H5CHO, nu(3) (nu = 1) of HCO, and levels nu <= 2, J <= 43 of CO are observed; the latter has an average rotational energy of approximately 13 kJ mol(-1) and vibrational energy of approximately 6 kJ mol(-1). Upon photolysis at 193 nm, similar distributions of energy are observed, except that the C6H5+HCO channel becomes the only major channel with a branching ratio of 0.82 +/- 0.10 and an increased proportion of the slow component; IR emission from levels nu(1) (nu = 1) and nu(3) (nu = 1 and 2) of HCO and nu <= 2, J <= 43 of CO are observed; the latter has an average energy similar to that observed in photolysis at 248 nm. The observed product yields at different dissociation energies are compared to statistical-theory predicted results based on the computed singlet and triplet potential-energy surfaces.
Unusually Long trans/gauche Conformational Equilibration Time during the Melting Process of BmimC1, a Prototype Ionic Liquid
(2011-11-05)
Okajima, Hajime
;
Hamaguchi, Hiro-o
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應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
The melting process of 1-butyl-3-methylimidazolium chloride (bmimC1), a prototype room-temperature ionic liquid, has been studied with fast low frequency Raman spectroscopy. Simultaneous tracing of the lattice vibrations and trans/gauche conformational marker bands reveals that the conformational change in the butyl group occurs a few seconds after the loss of lattice vibrations. This finding indicates that the alkyl chain interaction in bmimC1 is so strong that the butyl conformation hardly changes in the very early stage of melting.
Toroidal fullerenes with the Cayley graph structures
(2011-11-06)
Kang, Ming-Hsuan
;
應用數學系
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Department of Applied Mathematics
We classify all possible structures of fullerene Cayley graphs. We give each one a geometric model and compute the spectra of its finite quotients. Moreover, we give a quick and simple estimation for a given toroidal fullerene. Finally, we provide a realization of those families in three-dimensional space. (C) 2011 Elsevier B.V. All rights reserved.
Linear photon up-conversion of 450 meV in InGaN/GaN multiple quantum wells via Mn-doped GaN intermediate band photodetection
(2011-11-07)
Huang, Feng-Wen
;
Sheu, Jinn-Kong
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Lee, Ming-Lun
;
Tu, Shang-Ju
;
Lai, Wei-Chih
Up-converted heterostructures with a Mn-doped GaN intermediate band photodetection layer and an InGaN/GaN multiple quantum well (MQW) luminescence layer grown by metal-organic vapor-phase epitaxy are demonstrated. The up-converters exhibit a significant up-converted photoluminescence (UPL) signal. Power-dependent UPL and spectral responses indicate that the UPL emission is due to photo-carrier injection from the Mn-doped GaN layer into InGaN/GaN MQWs. Photons convert from 2.54 to 2.99 eV via a single-photon absorption process to exhibit a linear up-conversion photon energy of similar to 450 meV without applying bias voltage. Therefore, the up-conversion process could be interpreted within the uncomplicated energy level model. (C) 2011 Optical Society of America
Reactions between chlorine atom and acetylene in solid para-hydrogen: Infrared spectrum of the 1-chloroethyl radical
(2011-11-07)
Golec, Barbara
;
Lee, Yuan-Pern
;
應用化學系
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應用化學系分子科學碩博班
;
Department of Applied Chemistry
We applied infrared matrix isolation spectroscopy to investigate the reactions between Cl atom and acetylene (C(2)H(2)) in a para-hydrogen (p-H(2)) matrix at 3.2 K; Cl was produced via photodissociation at 365 nm of matrix-isolated Cl(2) in situ. The 1-chloroethyl radical (center dot CHClCH(3)) and chloroethene (C(2)H(3)Cl) are identified as the main products of the reaction Cl + C(2)H(2) in solid p-H(2). IR absorption lines at 738.2, 1027.6, 1283.4, 1377.1, 1426.6, 1442.6, and 2861.2 cm (1) are assigned to the 1-chloroethyl radical. For the reaction of Cl + C(2)D(2), lines due to the center dot CDClCH(2)D radical and trans-CHDCDCl are observed; the former likely has a syn-conformation. These assignments are based on comparison of observed vibrational wavenumbers and (13)C- and D-isotopic shifts with those predicted with the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ methods. Our observation indicates that the primary addition product of Cl + C(2)H(2), 2-chlorovinyl (center dot CHCHCl) reacts readily with a neighboring p-H(2) molecule to form center dot CHClCH(3) and C(2)H(3)Cl. Observation of center dot CDClCH(2)D and trans-CHDCDCl from Cl + C(2)D(2) further supports this conclusion. Although the reactivity of p-H(2) appears to be a disadvantage for making highly reactive free radicals in solid p-H(2), the formation of 1-chloroethyl radical indicates that this secondary reaction might be advantageous in producing radicals that are difficult to prepare from simple photolysis or bimolecular reactions in situ. (C) 2011 American Institute of Physics. [doi:10.1063/1.3653988]
Spectral modulation observed in Chl-a by ultrafast laser spectroscopy
(2011-11-07)
Du, Juan
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Nakata, Kazuaki
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Jiang, Yongliang
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Tokunaga, Eiji
;
Kobayashi, Takayoshi
Broadband real-time dynamic vibronic coupling in Chl-a were experimentally studied using few cycle laser pulses of 6.8fs duration and a 128-channnel lock-in amplifier. Thanks to the extreme temporal resolution benefitting from the ultrashort laser pulse, the real-time modulation of the electronic transition energy induced by the molecular vibrations were calculated by the time dependent first moments of the bleaching band. The transition energy was found to be modulated periodically with the same frequencies of molecular vibration found in the Fourier amplitude spectrum of the difference absorbance real-time traces. This was interpreted to be due to the difference in the effective transition energy associated with the wavepacket motion induced by the equilibrium positions of potential curves between the ground state and the excited state. Using the values, Huang-Rhys factors for several vibrational modes involved in the spectral modulation at the room-temperature have been determined. (C)2011 Optical Society of America
交大e-News第105期
(2011-11-07)
Secretariat
;
國立交通大學秘書室
Object image detection method
(2011-11-08)
Han Chin-Chuan
;
Chen Ying-Nong
The present invention discloses an object image detection method, which uses a coarse-to-fine strategy to detect objects. The method of the present invention comprises steps: acquiring an image and pre-processing the image to achieve dimensional reduction and information fusion; using a trained filter to screen features; and sequentially using a coarse-level MLP verifier and a fine-level MLP verifier to perform a neural network image detection to determine whether the features of the image match the features of the image of a target object. The present invention simultaneously uses three mainstream image detection methods, including the statistic method, neural network method and adaboost method, to perform image detection. Therefore, the present invention has the advantages of the rapidity of the adaboost method and the accuracy of the neural network method at the same time.
Wavelength-multiplex and space-multiplex holographic storage device
(2011-11-08)
Su Wei-Chia
;
Chen Yeh-Hung
;
Chung Te-Yuan
The present invention discloses a wavelength-multiplex and space-multiplex holographic storage device, which comprises a storage medium, a plurality of signal light beams and at least one reference light beam. The signal light beams have different wavelengths and illuminate the storage medium. The reference light beam illuminates the storage medium and interferes with the signal light beams to form a plurality of interference patterns. The interference patterns are respectively stored on different-depth storage layers of the storage medium. The present invention not only has a high access rate but also has a large storage capacity.
Donor-Acceptor Random Copolymers Based on a Ladder-Type Nonacyclic Unit: Synthesis, Characterization, and Photovoltaic Applications
(2011-11-08)
Chen, Chiu-Hsiang
;
Cheng, Yen-Ju
;
Chang, Chih-Yu
;
Hsu, Chain-Shu
;
應用化學系
We have developed a ladder-type multifused thienyl-phenylene-thienylene-phenylene-thienyl (TPTPT) unit where each thiophene ring is covalently fastened with the adjacent benzene rings by a carbon bridge, forming four cyclopentadiene rings embedded in a nonacyclic structure. This rigid and coplanar TPTPT building block was copolymerized with electron-deficient acceptors, dibromobenzothiadiazole (BT) or dibromodithienyldiketopyrrolopyrrole (DPP), via Stille polymerization. By varying the feed ratio of the monomers, a new series of random copolymers PTPTPTBT11, PTPTPTBT12, PTPTPTDPP11, PTPTPTDPP12, and PTPTPTDPP13 with tunable optical and electronic properties were prepared. The PTPTPTDPP12/PC(71)BM (1:4, w/w) based device exhibited the highest short circuit current (J(sc)) of 10.78 mA/cm(2) with a good power conversion efficiency (PCE) of 4.3% due to the much boarder absorption ability and the highest hole mobility of PTPTPTDPP12. The devices based on PTPTPTDPP13, PTPTPTDPP11, PTPTPTBT12, and PTPTPTBT11 polymers also displayed promising efficiencies of 4.1%, 3.6%, 3.1%, and 2.8%, respectively. Most importantly, PTPTPTDPP12 has been demonstrated as a superior low-band-gap material for polymer solar cell with inverted architecture, achieving a high PCE of 5.1%.
Method for parameter identification and parameter optimization of microspeakers
(2011-11-08)
Bai Mingsian R.
;
Chen Rong Liang
The present invention discloses a method for parameter identification and parameter optimization of microspeakers. Measurement procedures for identifying electromechanical constants of microspeaker and a GUI are developed to facilitate estimation of electroacoustic parameters of the microspeaker under test. In light of the thus identified microspeaker parameters, a parameter optimization procedure is carried out to obtain the design that attains the best acoustic performance with minimum harmonic distortion.
Object-based image search system and method
(2011-11-08)
Fu Hsin Chia
;
Xu Yeong Yuh
The present invention discloses an object-based image search system and method, whereby a user may visually specify query objects for retrieving relevant images without using any image-segmenting software tool. The method of the present invention comprises: specifying target feature points from sample images which are displayed in an image query interface and determining logic relationships of the target feature points; utilizing a feature-point checking program to correlate the target feature points with target objects; utilizing a feature-similarity calculating program to find out the images relevant to the target objects via the image feature parameters stored in a feature database; arranging and presenting the relevant images in sequence.
Axial couplings in heavy-hadron chiral perturbation theory at the next-to-leading order
(2011-11-09)
Detmold, William
;
Lin, C. -J. David
;
Meinel, Stefan
;
物理研究所
;
Institute of Physics
We present calculations of axial-current matrix elements between various heavy-meson and heavy-baryon states to the next-to-leading order in heavy-hadron chiral perturbation theory in the p-regime. When compared with data from lattice computations or experiments, these results can be used to determine the axial couplings in the chiral Lagrangian. Our calculation is performed in partially quenched chiral perturbation theory for both SU(4 vertical bar 2) and SU(6 vertical bar 3). We incorporate finite-size effects arising from a single Goldstone meson wrapping around the spatial volume. Results for full QCD with two and three flavors can be obtained straightforwardly by taking the sea-quark masses to be equal to the valence-quark masses. To illustrate the impact of our chiral perturbation theory calculation on lattice computations, we analyze the SU(2) full-QCD results in detail. We also study one-loop contributions relevant to the heavy-hadron strong-decay amplitudes involving final-state Goldstone bosons, and demonstrate that the quark-mass dependence of these amplitudes can be significantly different from that of the axial-current matrix elements containing only single-hadron external states.
METHOD FOR ANALOG PLACEMENT AND GLOBAL ROUTING CONSIDERING WIRING SYMMETRY
(2011-11-10)
JIANG Iris Hui-Ru
;
YANG Yu-Ming
A method for analog placement and global routing considering wiring symmetry performs a layout for a circuit which is described by a netlist having a set of devices and wires. First, the method inputs the netlist, and each device thereof has a design constraint and a corresponding priority. Based on the priorities, it performs a sorting on the devices to establish a constraint library. Then, based on the design constraint and corresponding priority of each device, the method establishes a hierarchical constraint tree. According to the hierarchical constraint tree, the method performs placement of each device, wherein possible shape of each device is represented by a shape curve. For each placement of the device, the method calculates a corresponding cost function. Then, it selects an optimum placement of the device according to the cost functions. The method establishes an RSMT for each wire and then performs an analog routing.
Energy-efficient uplink resource allocation for IEEE 802.16j transparent-relay networks
(2011-11-10)
Liang, Jia-Ming
;
Wang, You-Chiun
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Chen, Jen-Jee
;
Liu, Jui-Hsiang
;
Tseng, Yu-Chee
The IEEE 802.16j standard is defined to enhance WiMAX networks with relay capacity. Under the transparent mode, existing studies only target improving network throughput by increasing the transmission rates of mobile stations (MSs) and maximizing concurrent transmissions. However, using a higher transmission rate or allowing more concurrent transmissions could harm MSs in terms of their energy consumption, especially when they are battery-powered. In this paper, we consider the energy-conserved resource allocation problem in the uplink direction of an IEEE 802.16j network under the transparent mode. This problem asks how to arrange the frame usage with satisfying MSs' demands as the constraint and minimizing their total energy consumption as the objective. We prove this problem to be NP-complete and develop two energy-efficient heuristics, called demand-first allocation (DFA) and energy-first allocation (EFA) schemes. These heuristics employ a gradient-like search method to approximate the optimal solution. Specifically, DFA tries to satisfy MSs' demands first by using as less frame space as possible. Then, with the remaining frame space. DFA tries to save MSs' energy by lowering their transmission rates or adjusting their transmission paths. Viewed from a different perspective. EFA first allocates the frame space to MSs to consume the least energy. Since the total allocation may exceed the frame space. EFA then exploits spatial reuse and rate adjustment to pack all demands into one frame. simulation results show that our heuristics can approximate the ideal performance bounds and save up to 90% of MSs' energy as compared to existing results. (C) 2011 Elsevier B.V. All rights reserved.