Browsing by Issue Date, starting with "2007-02-14"

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Photodissociation dynamics of nitrobenzene and o-nitrotoluene
(2007-02-14)
Lin, Ming-Fu
;
Lee, Yuan T.
;
Ni, Chi-Kung
;
Xu, Shucheng
;
Lin, M. C.
Photodissociation of nitrobenzene at 193, 248, and 266 nm and o-nitrotoluene at 193 and 248 nm was investigated separately using multimass ion imaging techniques. Fragments corresponding to NO and NO2 elimination from both nitrobenzene and o-nitrotoluene were observed. The translational energy distributions for the NO elimination channel show bimodal distributions, indicating two dissociation mechanisms involved in the dissociation process. The branching ratios between NO and NO2 elimination channels were determined to be NO/NO2=0.32 +/- 0.12 (193 nm), 0.26 +/- 0.12 (248 nm), and 0.4 +/- 0.12(266 nm) for nitrobenzene and 0.42 +/- 0.12(193 nm) and 0.3 +/- 0.12 (248 nm) for o-nitrotoluene. Additional dissociation channels, O atom elimination from nitrobenzene, and OH elimination from o-nitrotoluene, were observed. New dissociation mechanisms were proposed, and the results are compared with potential energy surfaces obtained from ab initio calculations. Observed absorption bands of photodissociation are assigned by the assistance of the ab initio calculations for the relative energies of the triplet excited states and the vertical excitation energies of the singlet and triplet excited states of nitrobenzene and o-nitrotoluene. Finally, the dissociation rates and lifetimes of photodissociation of nitrobenzene and o-nitrotoluene were predicted and compared to experimental results. (c) 2007 American Institute of Physics.
Photodissociation dynamics of nitrobenzene and o-nitrotoluene
(2007-02-14)
Lin, Ming-Fu
;
Lee, Yuan T.
;
Ni, Chi-Kung
;
Xu, Shucheng
;
Lin, M. C.
Photodissociation of nitrobenzene at 193, 248, and 266 nm and o-nitrotoluene at 193 and 248 nm was investigated separately using multimass ion imaging techniques. Fragments corresponding to NO and NO2 elimination from both nitrobenzene and o-nitrotoluene were observed. The translational energy distributions for the NO elimination channel show bimodal distributions, indicating two dissociation mechanisms involved in the dissociation process. The branching ratios between NO and NO2 elimination channels were determined to be NO/NO2=0.32 +/- 0.12 (193 nm), 0.26 +/- 0.12 (248 nm), and 0.4 +/- 0.12(266 nm) for nitrobenzene and 0.42 +/- 0.12(193 nm) and 0.3 +/- 0.12 (248 nm) for o-nitrotoluene. Additional dissociation channels, O atom elimination from nitrobenzene, and OH elimination from o-nitrotoluene, were observed. New dissociation mechanisms were proposed, and the results are compared with potential energy surfaces obtained from ab initio calculations. Observed absorption bands of photodissociation are assigned by the assistance of the ab initio calculations for the relative energies of the triplet excited states and the vertical excitation energies of the singlet and triplet excited states of nitrobenzene and o-nitrotoluene. Finally, the dissociation rates and lifetimes of photodissociation of nitrobenzene and o-nitrotoluene were predicted and compared to experimental results. (c) 2007 American Institute of Physics.
Novel epoxy nanocomposite of low D-k introduced fluorine-containing POSS structure
(2007-02-15)
Wang, Yen-Zen
;
Chen, Wen-Yi
;
Yang, Chao-Chen
;
Lin, Chen-Lung
;
Chang, Feng-Chih
A nanoporous additives, polyhedral oilgomeric silisesquioxane containing eight functional hexafluorine groups, octakis(dimethylsiloxyhexafluoropropyl ether)silsesquioxane (OF) has been synthesized and blended with the UV-cured epoxy resin. The OF containing (10%) epoxy has significantly lower dielectric constant (2.65) than the plain epoxy (3.71). The incorporation of fluorine containing additives is well-known to reduce dielectric constant due to lower its polarizability. In addition, the presence of the bulky POSS structure is able to create additional free space or pores and further reduces the dielectric constant of the epoxy matrix. (c) 2007 Wiley Periodicals, Inc.
The effect of centaurein on interferon-gamma expression and Listeria infection in mice
(2007-02-15)
Chang, Shu-Lin
;
Yeh, Hsu-Hua
;
Lin, Yu-Shiun
;
Chiang, Yi-Ming
;
Wu, Tung-Kung
We previously found that centaurein enhanced IFN-gamma transcription in T cells. Here, we demonstrate that centaurein increased the IFN-gamma expression in T and NK cells and the serum IFN-gamma level in mice. Centaurein elevated the transcription of T-bet but not GATA-3, which is consistent with its effect on that of IFN-gamma but not IL-4. Additionally, centaurein effectively protected mice against Listeria infection. Moreover, centaurein per se or in combination with antibiotics could treat Listeria infection. Our mechanistic studies suggest that centaurein augments IFN-gamma expression via a transcriptional up-regulation of T-bet and that centaurein protects against or treats Listeria infection via a modulation of IFN-gamma expression. (c) 2006 Elsevier Inc. All rights reserved.
A competitive algorithm in searching for many edges in a hypergraph
(2007-02-15)
Chen, Ting
;
Hwang, Frank K.
;
應用數學系
;
Department of Applied Mathematics
We give a competitive algorithm to identify all d defective edges in a hypergraph with d unknown. Damaschke did the d = 1 case for 2-graphs, Triesch extended the d = 1 case to r-graphs, and Johann did the general d case for 2-graphs. So ours is the first attempt to solve the searching for defective edges problem in its full generality. Further, all the above three papers assumed d known. We give a competitive algorithm where d is unknown. (c) 2006 Elsevier B.V. All rights reserved.
監控薄膜厚度變化之方法
(2007-02-16)
趙于飛
;
王夢偉
;
郭俊儀
;
柳克強
;
林滄浪
本發明係揭露一種監控薄膜厚度變化之方法,係用於一相位調變式橢圓儀。此方法包含經由相位調變式橢圓儀及一訊號擷取系統獲得一薄膜之一直流訊號、一一倍頻及一二倍頻訊號,並將前述之訊號傳遞至一電腦裝置。再經由電腦裝置之一如儀控程式之程式以換算前述之訊號得到一橢圓參數。接著,引入橢圓參數以計算薄膜之一厚度週期解,並利用一數據化之一二維厚度表示法即時監控薄膜之厚度週期解的變化。同時,透過程式呈現此方法之一監控畫面於電腦裝置之一顯示單元上。
Effect of Al-trace degradation on Joule heating during electromigration in flip-chip solder joints
(2007-02-19)
Liang, S. W.
;
Chiu, S. H.
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
This study investigates the mechanism for the abrupt increase in temperature at later stages of electromigration in flip-chip solder joints. It is found that electromigration also occurs in Al traces when stressed by 0.6 A at 100 degrees C. Three-dimensional thermoelectrical simulation by finite element analysis was carried out to simulate the temperature distribution in solder joints with and without degradation of the Al trace. It is found that the degradation of the Al trace has substantial effect on the Joule heating of solder joints. This model can explain the serious Joule heating effect in the later stages of electromigration. (c) 2007 American Institute of Physics.
Wavelength switching transition in quantum dot lasers
(2007-02-19)
Wang, Hsing-Yeh
;
Cheng, Hsu-Chieh
;
Lin, Sheng-Di
;
Lee, Chien-Ping
;
電子工程學系及電子研究所
Control and the selection of the ground state emission and/or the excited state emission of an InAs quantum dot laser have been demonstrated. By controlling the currents injected into each section of a two-section cavity, switching between the ground state emission and the excited state emission with a separation of 100 nm was achieved. With a constant total current, either ground state lasing (similar to 1.3 mu m), excited state lasing (similar to 1.2 mu m), or dual state lasing can be obtained simply by adjusting the current ratio between the two sections. (c) 2007 American Institute of Physics.
Double-pass high-gain low-noise EDFA over Sand C+L-bands by tunable fundamental-mode leakage loss
(2007-02-19)
Hung, Chi-Ming
;
Chen, Nan-Kuang
;
Lai, Yinchieh
;
Sien, Chi
;
光電工程學系
We demonstrate a high-gain low-noise double-pass tunable EDFA over S- and C+L-bands by discretely introducing fundamental-mode leakage loss in a 16-m-long standard C-band Er3+-doped fiber. The amplified spontaneous emission at the wavelengths of longer than 1530 nm can be substantially attenuated by the ASE suppressing filters to maintain high population inversion and to squeeze out the optical gain for S- band signals. When the filters are disabled, the gain bandwidth immediately returns back to the C+L-bands. Under S-band operation, a 37 dB small signal gain and a minimum 4.84 dB noise figure at 1486.9 nm are achieved with a 980 nm pump power of 154 mW. (c) 2007 Optical Society of America.
Micro actuated grating for multi-beam optical pickups
(2007-02-19)
Lee, Chi-Hung
;
Chiu, Yi
;
Shieh, Han-Ping D.
;
電控工程研究所
;
光電工程學系
A stress-induced curved polysilicon actuator with a grating is achieved for the application of recordable optical pickups, which have been realized on a single silicon chip using a two-layer poly-silicon and one-layer silicon nitride micro-machining process. Three diffracted beams with equal intensity in each order from the grating were generated while applying a voltage to the actuator. The switching between the single beam and multiple beams can be applied for writing data and reading data in the disc, respectively. (c) 2007 Optical Society of America.
Infrared spectra of C2H2 under jet-cooled and para-H-2 matrix conditions
(2007-02-19)
Lee, Ying-Chi
;
Venkatesan, V.
;
Lee, Yuan-Pern
;
Macko, P.
;
Didiriche, K.
In spectra of jet-cooled C2H2 recorded with an FTIR spectrometer, the v(5), v(4) + v(5), v(3) and v(2) + v(4) + v(5) bands all exhibit an intensity distribution corresponding to similar to 6 K for rotation, with no evidence of nuclear spin conversion. Spectra of C2H2 isolated in solid p-H-2 show no evidence of rotation of C2H2. The strong interaction between v(3) and v(2) + v(4) + v(5) in the gas phase is diminished in solid p-H-2. Lines associated with dimer, trimer and tetramer of C2H2 are identified. Spectral features characteristic of solid state acetylene are observed under jet-cooled conditions. (c) 2007 Elsevier B.V. All rights reserved.
Use of Si+ pre-ion-implantation on Si substrate to enhance the strain relaxation of the GexSi1-x metamorphic buffer layer for the growth of Ge layer on Si substrate
(2007-02-19)
Hsieh, Y. C.
;
Chang, E. Y.
;
Luo, G. L.
;
Pilkuhn, M. H.
;
Tang, S. S.
Si+ pre-ion-implantation combined with a GexSi1-x metamorphic buffer structure for the growth of Ge layer on Si substrate is proposed. Enhanced strain relaxation of the GexSi1-x metamorphic buffer layer on Si substrate was achieved due to the introduction of the point defects by heavy dose Si+ pre-ion-implantation. Because of the strain relaxation enhancement and the interface blocking of the dislocations in the GexSi1-x metamorphic buffer structure, the total thickness of the buffer layers was only 0.45 mu m. No cross-hatch pattern was observed on the Ge surface and the dislocation density for the top Ge film was only 7.6x10(6) cm(-2). (c) 2007 American Institute of Physics.
Effect of ZnSe partial capping on the ripening dynamics of CdSe quantum dots
(2007-02-19)
Lai, Y. J.
;
Yang, C. S.
;
Chen, W. K.
;
Lee, M. C.
;
Chang, W. H.
The ripening dynamics of CdSe quantum dots (QDs) partially capped with ZnSe layer are investigated. Atomic force microscopy (AFM) images show that the ripening of QDs is dramatically accelerated by depositing a ZnSe partial capping layer. The driving force of ripening enhancement is attributed to the increasing strain energy with capping thickness. For a ZnSe partial capping layer of below 3 ML, photoluminescence exhibits a clear redshift with increasing ZnSe monolayers. It is attributed to the size of the CdSe QD increases with ZnSe partial capping, in a manner that is consistent with the results of the AFM study. (c) 2007 American Institute of Physics.
Post flight analysis of the surface plasmon resonance enhanced photoelastic modulated ellipsometry
(2007-02-20)
Chao, Yu-Faye
;
Han, Chien-Yuan
;
光電工程學系
;
Department of Photonics
A total internal reflection ellipsometer equipped with a photoelastic modulator (PEM) is installed to investigate the chemical activation and antibody immobilization process on thin gold films. We set up two detection channels in this configuration: one for real-time monitoring with a data rate of 1 set per second, and the other for post flight analysis with a data rate of 25,000 sets per second. More detailed information has been obtained through the post flight analysis technique during the chemical activation process. This surface plasmon resonance enhanced PEM ellipsometry provides higher sensitivity and temporal resolution. It is feasible to resolve a faster reaction such as chemical reaction or protein folding by the post flight analysis technique. (c) 2006 Elsevier B.V. All rights reserved.
Three-dimensional modeling of small-scale processes in the upper boundary layer bounded by a dynamic ocean surface
(2007-02-20)
Tsai, Wu-ting
;
Hung, Li-ping
;
土木工程學系
;
Department of Civil Engineering
[1] We present a numerical model for simulating boundary-layer turbulence bounded by a dynamic ocean surface and driven by wind stresses. The nonlinear boundary conditions are satisfied on the freely moving surface exactly without any approximation. The time-dependent physical space is mapped onto a rectangular computational domain where the momentum equations are integrated in time for the velocity field and the solenoidal condition is satisfied by solving the transformed pressure Poisson equation. The developed model is validated with a progressive gravity wave and with a gravity-capillary wave. The model capabilities for resolving surface waves of various length scales, ranging from the gravity waves to the capillary ripples, and the nonlinear interactions among the waves are highlighted by simulating the evolution of two-dimensional short-crested gravity-capillary waves and the development of a gravity wave train into crescent patterns. The potential applicability of the model for studying the wind-driven aqueous near-surface layer is then demonstrated. The simulation results reveal fine surface structures, including microscale breaking waves and streamwise velocity streaks, which have been observed in the laboratory and field experiments.
Illumination system for wire bonding inspection
(2007-02-20)
Perng, Der-Baau
;
Chou, Cheng-Chuan
;
Lee, Shu-Ming
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
A novel lighting system was devised for 3D defect inspection in the wire bonding process. Gold wires of 20 mu m in diameter were bonded to connect the integrated circuit (IC) chip with the substrate. Bonding wire defects can be classified as 2D type and 3D type. The 2D-type defects include missed, shifted, or shorted wires. These defects can be inspected from a 2D top-view image of the wire. The 3D-type bonding wire defects are sagging wires, and are difficult to inspect from a 2D top-view image. A structured lighting system was designed and developed to facilitate all 2D-type and 3D-type defect inspection. The devised lighting system can be programmed to turn the structured LEDs on or off independently. Experiments show that the devised illumination system is effective for wire bonding inspection and will be valuable for further applications.
影像式物件追蹤方法
(2007-02-21)
傅智銘
;
黃仲陵
本發明提出一種影像式物件追蹤方法，其特徵為兩階段式的獲取物件區域機率，第一階段是以像素特徵為基礎，第二階段是以候選區塊物件形狀機率為基礎來追蹤與獲取物件區域。本發明可以將系統初始化的動作標準化運用在不同的環境下，且利用運算量低的無標籤追蹤技術，可以有效得到動態軌跡，而不需藉助手套或標記的輔助，用以得到物件的區域與軌跡，作為輔助性人機介面。
Monte Carlo simulations of stress relaxation of entanglement-free Fraenkel chains. II. Nonlinear polymer viscoelasticity
(2007-02-21)
Lin, Y. -H.
;
Das, A. K.
;
應用化學系
;
Department of Applied Chemistry
The nonlinear viscoelastic behavior of the Fraenkel-chain model is studied with respect to the constitutive equation of the Rouse model. Distinctly different from the results of the Rouse model, the Fraenkel-chain model gives the following characteristic nonlinear behavior: (a) The two distinct dynamic modes in the relaxation modulus G(S)(t,lambda)-as observed in the linear region reported in Paper I [Y.-H. Lin and A. K. Das, J. Chem. Phys. 126, 074902 (2007), preceding paper]-or in the first normal-stress difference function G(Psi 1)(t,lambda) are shown to have different strain dependences: strain hardening for the fast mode and strain softening for the slow mode. (b) The Lodge-Meissner relation G(S)(t,lambda)=G(Psi 1)(t,lambda) holds over the whole time range, which has been shown both analytically and by simulation. (c) The second normal-stress difference is nonzero, being positive in the fast-mode region and negative in the slow-mode region. The comparisons between orientation and stress for all tensor components consistently confirm the strong correlation of the slow mode as well as its entropic nature with the segmental-orientation anisotropy as shown in the linear region studied in Paper I. A consequence of this correlation is the applicability of the stress-optical rule in the slow-mode region. This also leads to the expectation that the damping function h(lambda)=G(S)(t,lambda)/G(S)(t,lambda -> 0) and the ratio between the first and second normal-stress differences, N-2(t,lambda)/N-1(t,lambda), are described by the orientation tensor which has the same form as that given by Doi and Edwards [J. Chem. Soc. Faraday Trans. 2 74, 1789 (1978); 74, 1802 (1978)] with independent-alignment approximation for an entangled system. The similarity between the slow mode of an entanglement-free Fraenkel-chain system and the terminal mode of an entangled polymer system as observed in the comparison of theory, simulation, and experiment suggests that the close correlation of the entropic nature of the mode with the orientation anisotropy-as of the Fraenkel segment or the primitive step in the Doi-Edwards theory-is a generally valid physical concept in polymer viscoelasticity. (c) 2007 American Institute of Physics.
Mobility asymmetry in InGaAs/InAlAs heterostructures with InAs quantum wires
(2007-02-21)
Lin, Z. C.
;
Hsieh, W. H.
;
Lee, C. P.
;
Suen, Y. W.
;
電子工程學系及電子研究所
Strong asymmetry of electron mobility in InGaAs/InAlAs heterostructures (lattice matched to InP) with the presence of InAs quantum wires was observed. Self-assembled InAs quantum wires, embedded in an InGaAs matrix close to the hetero-interface, has a strong effect in electron conduction in the interface channel. The low temperature mobility for electrons moving parallel to the quantum wires is much higher than that of electrons moving perpendicular to the wires. The asymmetry in mobility is attributed to the difference in scattering cross section of the quantum wires in these two directions.
資料錯誤率量測裝置及其偽隨機碼產生器
(2007-02-21)
陳巍仁
;
黃冠勝
一種資料錯誤率量測裝置及其偽隨機碼產生器。此資料錯誤率量測裝置包括發送端偽隨機碼產生器、主偽隨機碼產生器、僕偽隨機碼產生器、比較器以及計數單元。發送端偽隨機碼產生器產生平行N位元之原偽隨機碼(N為大於1之整數)，其中待測物接收原偽隨機碼後輸出平行N位元之待測碼。主偽隨機碼產生器產生平行N位元之主偽隨機碼，以及僕偽隨機碼產生器產生平行N位元之僕偽隨機碼。比較器接收並比較待測碼、主偽隨機碼以及僕偽隨機碼是否相同，以及輸出比較結果。計數單元耦接至比較器，用以依據比較結果計數資料錯誤次數。