Browsing by Issue Date, starting with "2006-10-07"

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The bending vibrational levels of the acetylene cation: A case study of the Renner-Teller effect in a molecule with two degenerate bending vibrations
(2006-10-07)
Tang, Sheunn-Jiun
;
Chou, Yung-Ching
;
Lin, Jim Jr-Min
;
Hsuc, Yen-Chu
;
應用化學系
Forty three vibronic levels of C2H2+, X (2)Pi(u), with upsilon(4)=0-6, upsilon(5)=0-3, and K=0-4, lying at energies of 0-3520 cm(-1) above the zero-point level, have been recorded at rotational resolution. These levels were observed by double resonance, using 1+1(') two-color pulsed-field ionization zero-kinetic-energy photoelectron spectroscopy. The intermediate states were single rovibrational levels chosen from the A (1)A(u), 4 nu(3) (K=1-2), 5 nu(3) (K=1), nu(2)+4 nu(3) (K=0), and 47 206 cm(-1) (K=1) levels of C2H2. Seven of the trans-bending levels of C2H2+ (upsilon(4)=0-3, K=0-2) had been reported previously by Pratt [J. Chem. Phys. 99, 6233 (1993)]; our results for these levels agree well with theirs. A full analysis has been carried out, including the Renner-Teller effect and the vibrational anharmonicity for both the trans- and cis-bending vibrations. The rotational structure of the lowest 16 vibronic levels (consisting of the complete set of levels with upsilon(4)+upsilon(5)<= 2, except for the unobserved upper (2)Pi(u) component of the 2 nu(4) overtone) could be fitted by least squares using 16 parameters to give an rms deviation of 0.21 cm(-1). The vibronic coupling parameter epsilon(5) (about whose magnitude there has been controversy) was determined to be -0.0273(7). For the higher vibronic levels, an additional parameter, r(45), was needed to allow for the Darling-Dennison resonance between the two bending manifolds. Almost all the observed levels of the upsilon(4)+upsilon(5)=3 and 4 polyads (about half of the predicted number) could then be assigned. In a final fit to 39 vibronic levels with upsilon(4)+upsilon(5)<= 5, an rms deviation of 0.34 cm(-1) was obtained using 20 parameters. An interesting finding is that Hund's spin-coupling cases (a) and (b) both occur in the Sigma(u) components of the nu(4)+2 nu(5) combination level. The ionization potential of C2H2 (from the lowest rotational level of the ground state to the lowest rotational level of the cation) is found to be 91 953.77 +/- 0.09 cm(-1) (3 sigma). (c) 2006 American Institute of Physics.
Crossed molecular beam studies on the reaction dynamics of O(D-1)+N2O
(2006-10-07)
Lu, Yu-Ju
;
Liang, Chi-Wei
;
Lin, Jim J.
;
應用化學系
;
Department of Applied Chemistry
The reaction of oxygen atom in its first singlet excited state with nitrous oxide was investigated under the crossed molecular beam condition. This reaction has two major product channels, NO+NO and N-2+O-2. The product translational energy distributions and angular distributions of both channels were determined. Using oxygen-18 isotope labeled O(D-1) reactant, the newly formed NO can be distinguished from the remaining NO that was contained in the reactant N2O. Both channels have asymmetric and forward-biased angular distributions, suggesting that there is no long-lived collision complex with lifetime longer than its rotational period. The translational energy release of the N-2+O-2 channel (f(T)=0.57) is much higher than that of the NO+NO channel (f(T)=0.31). The product energy partitioning into translational, rotational, and vibrational degrees of freedom is discussed to learn more about the reaction mechanism. The branching ratio between the two product channels was estimated. The (N2O)-N-46 product of the isotope exchange channel, O-18+(N2O)-N-44 -> O-16+(N2O)-N-46, was below the detection limit and therefore, the upper limit of its yield was estimated to be 0.8%. (c) 2006 American Institute of Physics.
Dissociation of heme from gaseous myoglobin ions studied by infrared multiphoton dissociation spectroscopy and Fourier-transform ion cyclotron resonance mass spectrometry
(2006-10-07)
Wang, Yi-Sheng
;
Sabu, Sahadevan
;
Wei, Shih-Chia
;
Kao, C. -M. Josh
;
Kong, Xianglei
Detachment of heme prosthetic groups from gaseous myoglobin ions has been studied by collision-induced dissociation and infrared multiphoton dissociation in combination with Fourier-transform ion cyclotron resonance mass spectrometry. Multiply charged holomyoglobin ions (hMb(n+)) were generated by electrospray ionization and transferred to an ion cyclotron resonance cell, where the ions of interest were isolated and fragmented by either collision with Ar atoms or irradiation with 3 mu m photons, producing apomyoglobin ions (aMb(n+)). Both charged heme loss (with [Fe(III)-heme](+) and aMb((n-1)+) as the products) and neutral heme loss (with [Fe(II)-heme] and aMb(n+) as the products) were detected concurrently for hMb(n+) produced from a myoglobin solution pretreated with reducing reagents. By reference to E-a=0.9 eV determined by blackbody infrared radiative dissociation for charged heme loss of ferric hMb(n+), an activation energy of 1.1 eV was deduced for neutral heme loss of ferrous hMb(n+) with n=9 and 10. (c) 2006 American Institute of Physics.
弔民伐罪
(2006-10-08)
管管
Improvement of InGaN/GaN light emitting diode performance with a nano-roughened p-GaN surface by excimer laser-irradiation
(2006-10-10)
Huang, Hung-Wen
;
Kao, C. C.
;
Chu, J. T.
;
Liang, W. D.
;
Kuo, H. C.
In this paper, we reported the InGaN/GaN light emitting diode (LED) with a nano-roughened top p-GaN surface which caused by KrF excimer laser-irradiation. Comparing with the conventional LED, the brightness of InGaN/GaN light emitting diode (LED) was raised by a factor of 1.25 at 20 mA after KrF excimer laser-irradiation (250 mJ cm(-2) at 248 nm for 25 ns). Meanwhile, the operation voltage of InGaN/GaN LED was reduced from 3.55 to 3.3 V at 20 mA with 29% reduction in the series resistance. The causes for the brightness increase can be attributed to laser-irradiation induced nano-roughening of p-GaN surface. The reduction in the series resistance can be attributed to the increased contact area of nano-roughened surface and higher hole concentration after laser-irradiation. (c) 2005 Published by Elsevier B.V.
Measurement of 2,4-toluene diisocyanate concentrations by different samplers
(2006-10-11)
Tsai, Chuen-Jinn
;
Lin, Hsi-Chen
;
Shih, Tung-Sheng
;
Chang, Kai-Chung
;
Hung, I.-Fu
The standard sampling methods for toluene diisocyanate (TDI) only collect total TDI without separating the aerosol and gas phases. There are few other samplers, such as the dual filter, triple filter and annular denuder systems (ADS), which are able to sample the aerosol and gas phases simultaneously. This field study was conducted at two workplaces to access the total 2,4-TDI and the gaseous and aerosol TDI concentrations by different samplers simultaneously. In addition to the standard sampling time of 15 min, sampling was done for 30 and 60 min to study the effect of sampling time on the measured 2,4-TDI concentrations. Test results at two workplaces show that gas-phase 2,4-TDI is the predominant species and the aerosol phase concentration is very small. The measurements using various samplers show that the sampling time influences the sampled TDI concentration considerably which may be due to reaction of TDI with water vapor and polyo in the sampling process. It is evident that as sampling time increases the TDI concentration decreases. Laboratory test was also conducted using pure gas-phase 2,4-TDI to confirm the sampling time effect on the measured concentrations found in the field study. (c) 2006 Elsevier B.V. All rights reserved.
多輸入多輸出多載波分碼多重進接通訊系統之架構及其方法
(2006-10-11)
鄧俊宏
;
吳卓諭
;
李大嵩
本發明提供一種多輸入多輸出(MIMO)方法及其裝置，適用於多路徑環境下之下鏈高速多載波分碼多重進接系統，用以同時獲得頻譜效益與多樣增益。本發明之收發機包含下列程序，首先，欲傳輸資料同時被分送至多個平行資料串，每個資料串被空間時間區塊編碼處理之，以達到空間多樣功能；其次，編碼後資料串再經由預先設計的空間-路徑展開碼進行多用戶與多路徑間干擾消除，並達到在多路徑上多工傳送資料之功能，再藉由多天線發射資料；然後，在每個接收端，經由簡單的匹配濾波器進行解展頻資料，再利用線性合成器與BLAST(類似多用戶)檢測器分離出互相干擾之訊號，並且獲得分送增益。
光學元件中微透鏡與微孔自我對準的製作方法
(2006-10-11)
邱一
;
徐文祥
;
張育儒
本發明係揭露一種光學元件中微透鏡與微孔自我對準的製作方法，其係在一透明基板上之不透明薄膜中製作微孔與環型孔，再以背向曝光自我對準技術將微孔與高分子材料所構成之微透鏡精確地整合，不需任接合步驟，且能以較習知技術更為簡單的方式，藉由一連貫之批次生產製造流程將微透鏡與微孔精確地對準整合。由於微孔與環型孔屬於同心圓結構，且為同一步驟製作而成，因此藉由背向曝光方法，即能將微透鏡與微孔精確地對準整合。利用本發明製作出的微透鏡與微孔之整合結構，在光學存取或光學測量裝置應用上，可有效提高其光學解析度與效能。
快速鎖定時脈之資料回復電路
(2006-10-11)
陳巍仁
;
魏進元
本發明提供一種快速鎖定時脈之資料回復電路，其係採用二倍超取樣技術，其內部電路包含多相位輸出之鎖相迴路係產生複數相位θn，而相位內插器將所擷取相位θn及相位θn+2之信號計算合成出取樣相位Φn，再由相位偵測器以取樣相位擷取一資料與輸入資料校準比對產生一上/下修正信號，利用計數器將上/下修正信號進行累計產生一修正權值k，且將修正權值k輸出至相位內插器內以修正取樣相位。而為減少時脈回復過程所耗費時間，本發明另提出二位元搜尋法及二倍速超取樣之資料回復電路架構，藉此大幅減少鎖定所需時間，同時利用多相位分時平行取樣技術，進而達到高速操作及低功率消耗之目的。
Phenylalanine 445 within oxidosqualene-lanosterol cyclase from Saccharomyces cerevisiae influences C-ring cyclization and deprotonation reactions
(2006-10-12)
Wu, Tung-Kung
;
Liu, Yuan-Ting
;
Chiu, Feng-Hsuan
;
Chang, Cheng-Hsiang
;
生物科技學系
We describe the Saccharomyces cerevisiae oxidosqualene - lanosterol cyclase Phe445 site-saturated mutants that generate truncated tricyclic and altered deprotonation product profiles. Among these mutants, only polar side-chain group substitutions genetically complemented yeast viability and produced spatially related product diversity, supporting the Johnson model that cation - pi interactions between a carbocationic intermediate and an enzyme can be replaced by an electrostatic or polar side chain to stabilize the cationic intermediate, but with product differentiation.
Miniature inductor suitable for integrated circuits
(2006-10-12)
Kuo, Chien-Nan
;
Ma, Chien-Chia
A miniature inductor suitable for integrated circuits comprises a semiconductor substrate having a coplanar strip line and a plurality of metal-insulator-metal (MIM) capacitors, wherein the plurality of MIM capacitors are connected between the transmission lines of the coplanar strip line in parallel, and the coplanar strip line connected with the MIM capacitors further comprises a crossed planar strip line structure or a shifted planar strip line structure. The present invention reduces the occupied area for an inductor by adding the MIM capacitors and folding the transmission lines, and alleviates the quality factor degradation of the inductor caused by substrate loss.
Location-based incentive pricing for tree-based relaying in multi-hop cellular networks
(2006-10-12)
Lo, Chi-Chun
;
Lin, Ming-Hua
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Multi-hop cellular networks that integrate the characteristics of both cellular and mobile ad hoc networks have received increasing attention. Providing incentives to foster cooperation among nodes is an important prerequisite for the success of the multi-hop cellular networks. In this paper, we present a location-based incentive pricing scheme to enhance service availability for tree-based relaying topology. The proposed scheme adjusts the price of feedback incentives based on the degree of the mobile nodes contributing to successful hop-by-hop connections. Simulation results indicate that the location-based incentive pricing scheme results in higher service availability than the fixed-rate pricing scheme under different relationships between price of feedback and willingness of forwarding packets. Moreover, the proposed pricing scheme shifts incentives from the nodes of low importance to the nodes of high importance in the routing topology so that it increases service availability without additional costs. (c) 2006 Elsevier B.V. All rights reserved.
Phase formation and microwave dielectric properties of Pb2+ and Sr2+ doped La4Ti9O24 ceramics
(2006-10-12)
Liu, Yuan-Wen
;
Lin, Pang
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Phase formation and microwave dielectric properties of the Pb2+ and Sr2+ doped La4Ti9O24 ceramics were investigated. Using electron diffraction and Rietveld analysis of the X-ray powder diffraction patterns, we show that the increase in the concentration of Pb2+ and Sr2+ doping results in the structural transition from La4Ti9O24 to a La2/3TiO3-type phase (Ibmm, No. 74). A change in the crystalline phase considerably affects the microwave dielectric properties, increasing the epsilon(r) from 37 to 130, reducing Q x f from 25.000 to 5500, and increasing temperature coefficient of the resonant frequency (TCF) from 15 to 300 ppm/degrees C. (C) 2006 Elsevier Ltd. All rights reserved.
Crystal structure of rubredoxin from Desulfovibrio gigas to ultra-high 0.68 angstrom resolution
(2006-10-13)
Chen, Chun-Jung
;
Lin, Yi-Hung
;
Huang, Yen-Chieh
;
Liu, Ming-Yih
;
生物科技學系
Rubredoxin (D.g. Rd) is a small non-heme iron-sulfur protein shown to function as a redox coupling protein from the sulfate reducing bacteria Desulfovibrio gigas. The protein is generally purified from anaerobic bacteria in which it is thought to be involved in electron transfer or exchange processes. Rd transfers an electron to oxygen to form water as part of a unique electron transfer chain, composed by NADH:rubredoxin oxidoreductase (NRO), rubredoxin and rubredoxin: oxygen oxidoreductase (ROO) in D.g. The crystal structure of D.g. Rd has been determined by means of both a Fe single-wavelength anomalous dispersion (SAD) signal and the direct method, and refined to an ultra-high 0.68 angstrom resolution, using X-ray from a synchrotron. Rd contains one iron atom bound in a tetrahedral coordination by the sulfur atoms of four cysteinyl residues. Hydrophobic and it pi-pi interactions maintain the internal Rd folding. Multiple conformations of the iron-sulfur cluster and amino acid residues are observed and indicate its unique mechanism of electron transfer. Several hydrogen bonds, including N-H(...)SG of the iron-sulfur, are revealed clearly in maps of electron density. Abundant waters bound to C-O peptides of residues Val8, Cys9, Gly10, Ala38, and Gly43, which may be involved in electron transfer. This ultra-high-resolution structure allows us to study in great detail the relationship between structure and function of rubredoxin, such as salt bridges, hydrogen bonds, water structures, cysteine ligands, iron-sulfur. cluster, and distributions of electron density among activity sites. For the first time, this information will provide a clear role for this protein in a strict anaerobic bacterium. (c) 2006 Elsevier Inc. All rights reserved.
Photodissociation dynamics of fluorobenzene (C6H5F) at 157 and 193 nm: Branching ratios and distributions of kinetic energy
(2006-10-14)
Lee, Shih-Huang
;
Wu, Chia-Yan
;
Yang, Sheng-Kai
;
Lee, Yuan-Pern
;
應用化學系
Following photodissociation of fluorobenzene (C6H5F) at 193 and 157 nm, we detected the products with fragmentation-translational spectroscopy by utilizing a tunable vacuum ultraviolet beam from a synchrotron for ionization. Between two primary dissociation channels observed upon irradiation at 193 (157) nm, the HF-elimination channel C6H5F -> HF+C6H4 dominates, with a branching ratio of 0.94 +/- 0.02 (0.61 +/- 0.05) and an average release of kinetic energy of 103 (108) kJ mol(-1); the H-elimination channel C6H5F -> H+C6H4F has a branching ratio of 0.06 +/- 0.02 (0.39 +/- 0.05) and an average release of kinetic energy of 18.6 (26.8) kJ mol(-1). Photofragments H, HF, C6H4, and C6H4F produced via the one-photon process have nearly isotropic angular distributions. Both the HF-elimination and the H-elimination channels likely proceed via the ground-state electronic surface following internal conversion of C6H5F; these channels exhibit small fractions of kinetic energy release from the available energy, indicating that the molecular fragments are highly internally excited. We also determined the ionization energy of C6H4F to be 8.6 +/- 0.2 eV. (c) 2006 American Institute of Physics.
Dual-band multiplexer/demultiplexer with photonic-crystal-waveguide couplers for bidirectional communications
(2006-10-15)
Chien, Forest Shih-Sen
;
Cheng, Sue- Cheng
;
Hsu, Yu-Ju
;
Hsieh, Wen-Feng
;
光電工程學系
An ultrashort photonic-crystal-waveguide (PCW) coupler is numerically designed for dual-band multiplexing/demultiplexing (Muxing/Demuxing). The PCW coupler consists of two line defects of reduced rods in a triangular lattice and Muxing/Demuxing is implemented by the distinction between coupling and decoupling of PCWs. Since waves tend to highly localize within the reduced rods, the backward coupling is suppressed and the efficiency of Muxing/Demuxing is enhanced as compared with the void-rod PCWs. The coupler is utilized to build a bidirectional system for dual-band duplex communications. (c) 2006 Elsevier B.V. All rights reserved.
Effect of uniaxial strain on anisotropic diffusion in silicon
(2006-10-16)
Chen, Ming-Jer
;
Sheu, Yi-Ming
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A physical model is directly extended from the thermodynamic framework to deal with anisotropic diffusion in uniaxially stressed silicon. With the anisotropy of the uniaxial strain induced activation energy as input, two fundamental material parameters, the activation volume and the migration strain anisotropy, can be quantitatively determined. When applied to boron, a process- device coupled simulation is performed on a p-type metal-oxide-semiconductor field-effect transistor undergoing uniaxial stress in a manufacturing process. The resulting material parameters have been found to be in satisfactory agreement with values presented in the literature. (c) 2006 American Institute of Physics.
Convergence of phase noise in DPSK transmission systems by novel phase noise averagers
(2006-10-16)
Wei, Chia Chien
;
Chen, Jason (Jyehong)
;
光電工程學系
;
Department of Photonics
This investigation proposes a novel all-optical phase noise averager to reduce residual phase noise in the differential phase-shift keying (DPSK) transmission system with phase-preserving amplitude regenerators. The proposed phase noise averager is based on a phase-sensitive amplifier but does not require an extra phase-locking optical pump beam. It can increase the correlation between the phase noises of neighboring bits and greatly reduce the differential phase noise in the transmission system. Independently of the cascaded spans, analytical analysis demonstrates that, in the DPSK system with repeated averagers, the total differential phase noise will be less than that before the first averager. Theoretical analysis and numerical simulation are carried out and confirm the significant improvement of DPSK signals using the proposed novel phase noise averagers. (c) 2006 Optical Society of America
具銅金屬化之複合物半導體元件
(2006-10-16)
張翼
;
張尚文
;
李承士
本發明係為一具銅金屬化之複合物半導體元件，結構為異質接面雙載子電晶體(HBT)結構，當基板為砷化鎵基板時，其歐姆接觸層之材料為鈀／鍺／氮化鎢／銅或鉑／鈦／鉑／銅，而金屬連接線為鈦／鉑／銅；若基板為磷化銦基板時，歐姆接觸層之材料為鈦／鉑／銅或鉑／鈦／鉑／銅，金屬連接線為鈦／鉑／銅，藉由具有較佳散熱特性之銅取代金，可增加其散熱效果，進而增加元件的可靠度。
Luminescence properties of wurtzite AlN nanotips
(2006-10-16)
Shi, Shih-Chen
;
Chen, Chia Fu
;
Chattopadhyay, Surojit
;
Chen, Kuei-Hsien
;
Ke, Bo-Wen
The optical properties of aluminum nitride nanotips (AlNNTs) synthesized via vapor transport and condensation process have been studied by cathodoluminescence, photoluminescence (PL), thermoluminescence (TL), and UV absorption measurements. Two defect related transitions around 2.1 and 3.4 eV and an excitonic feature at 6.2 eV were identified. Compared to the AlN macropowders, the AlNNTs showed a blueshift (+0.2 eV) of the similar to 3.2 eV peak. Analysis of both PL and TL excitation measurements indicated the existence of subband gap multiple energy levels in AlNNTs. A significant TL intensity even at 145 degrees C suggests possible ultraviolet detector and dosimetric applications of these AlNNTs. (c) 2006 American Institute of Physics.