Browsing by Issue Date, starting with "2009-03-05"

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On the calculation of the dissociation rate constant of the water dimer by the ab initio anharmonic RRKM theory
(2009-03-05)
Yao, L.
;
He, R. X.
;
Mebel, A. M.
;
Lin, S. H.
;
應用化學系
The dissociation rate constant of the water dimer was calculated by using the method proposed by Yao and Lin (YL method). The dividing surface method and RRKM theory are used to calculate the pseudo transition state and the rate constant, respectively. For the canonical case at temperature range of 243-1000 K and for the microcanonical system at total energy 1411-4000 cm(1), the anharmonic rate constant, around 10(9)-10(11) s(1), is close to the experimental prediction. The present results indicate that the anharmonic effect should be included and YL method is suitable for calculating dissociation rate constants of such small flexible water cluster. (C) 2009 Elsevier B. V. All rights reserved.
Self-Assembled Fernlike Microstructures of Polyhedral Oligomeric Silsesquioxane/Gold Nanoparticle Hybrids
(2009-03-05)
Lu, Chu-Hua
;
Kuo, Shiao-Wei
;
Huang, Chih-Feng
;
Chang, Feng-Chih
;
應用化學系
We have used a thiol-functionalized polyhedral oligomeric silsesquioxane (SH-POSS) as a protective group for the preparation of POSS-protected gold nanoparticles (POSS-Au NPs). The organic/inorganic hybrid SH-POSS NPs exhibited an interesting platelike morphology arising from steric hindrance between the isobutyl groups of SH-POSS. An XRD study of the SH-POSS crystal revealed the relatively large interstice (1.64 nm lattice constant a > 1.3 nm diameter SH-POSS) on the basal plane of the unit cell, which resulted in a platelike morphology having lateral dimensions on the order of a few micrometers and thicknesses of a few hundred nanometers. In addition to behaving as a stabilizer for the preparation of Au NPs, an excess of SH-POSS colloids led to the formation of a crystalline template that incorporated the POSS-Au hybrid NPs on its surface, providing a unique fernlike microstructure. After removal of the POSS template (through sublimation and decomposition to a silica char) at 350 degrees C in air for I h, nanosized Au islands having diameters of 50-100 nm and thicknesses of 2-20 nm were sintered onto the substrate. As a result, SH-POSS is an excellent protective group for the preparation of Au NPs of high stability in the powder state. In addition, we suspect that SH-POSS crystals could be used to disperse Au NPs onto substrates for a wide range of applications (e.g., Au catalysts).
交大e-News第043期
(2009-03-05)
Secretariat
;
國立交通大學秘書室
Adsorption Configurations and Decomposition Pathways of Boric Acid on TiO(2) Rutile (110) Surface: A Computational Study
(2009-03-05)
Raghunath, P.
;
Lin, M. C.
;
應用化學系分子科學碩博班
;
Institute of Molecular science
We have investigated the adsorption and reactions of the monomer and dimer of B(OH)(3) on TiO(2) rutile (110) surface by first-principles calculations. The most stable adsorption structure for B(OH)(3) On the surface is a molecular monodentate configuration, with one hydrogen bonded to a neighboring surface bridging oxygen with an adsorption energy of 20.1 kcal/mol. The adsorbed B(OH)(3) molecule can dissociate into the bidentate adsorption configuration, Ti-OB(OH)O-Ti(a), in which the -OB(OH)O- moiety binds to the surface through two Ti-O bonds with the two dissociated H atoms on neighboring bridged surface oxygen atoms following stepwise H-migration. Notably, the adsorption energy for Ti-OB(OH)O-Ti(a) with 2 H on two O(b) surface atoms is 134.6 kcal/mol. In the case of dimer there are two identical molecules similar to monodentate configuration of B(OH)(3) adsorbed on two 5-fold-coordinated Ti atoms of the surface with an adsorption energy of 37.9 kcal/mol. Following intramolecular dehydration and successive migrations of protons from two OH groups to neighboring Ob sites, very stable Ti-OB(OH)OB(OH)O-Ti adsorbate can be readily formed with 141.1 kcal/mol binding energy. Both Ti-OB(OH)O-Ti(a) and Ti-OB(OH)OB(OH)O-Ti(a) adsorbates can be ideally employed as linkers between semiconductor quantum dots such as metal nitride or selenides and TiO(2) nanoparticles by pretreatment of nanoparticle films with B(OH)(3). A similar study on the adsorption and reactions of B(OH)(3) on anatase (101) surface has been recently reported. The most noticeable difference is that B(OH)(3) and its dimer on the rutile surface have slightly higher binding energies than those on the anatase surface and that the rutile surface is more effective for proton migration from the acid to the surface O-atom.
Adsorption Configurations and Decomposition Pathways of Boric Acid on TiO2 Rutile (110) Surface: A Computational Study
(2009-03-05)
Raghunath, P.
;
Lin, M. C.
;
應用化學系分子科學碩博班
;
Institute of Molecular science
We have investigated the adsorption and reactions of the monomer and dimer of B(OH)(3) on TiO2 rutile (110) surface by first-principles calculations. The most stable adsorption structure for B(OH)(3) On the surface is a molecular monodentate configuration, with one hydrogen bonded to a neighboring surface bridging oxygen with an adsorption energy of 20.1 kcal/mol. The adsorbed B(OH)(3) molecule can dissociate into the bidentate adsorption configuration, Ti-OB(OH)O-Ti(a), in which the -OB(OH)O- moiety binds to the surface through two Ti-O bonds with the two dissociated H atoms on neighboring bridged surface oxygen atoms following stepwise H-migration. Notably, the adsorption energy for Ti-OB(OH)O-Ti(a) with 2 H on two O-b surface atoms is 134.6 kcal/mol. In the case of dimer there are two identical molecules similar to monodentate configuration of B(OH)(3) adsorbed on two 5-fold-coordinated Ti atoms of the surface with an adsorption energy of 37.9 kcal/mol. Following intramolecular dehydration and successive migrations of protons from two OH groups to neighboring Ob sites, very stable Ti-OB(OH)OB(OH)O-Ti adsorbate can be readily formed with 141.1 kcal/mol binding energy. Both Ti-OB(OH)O-Ti(a) and Ti-OB(OH)OB(OH)O-Ti(a) adsorbates can be ideally employed as linkers between semiconductor quantum dots such as metal nitride or selenides and TiO2 nanoparticles by pretreatment of nanoparticle films with B(OH)(3). A similar study on the adsorption and reactions of B(OH)(3) on anatase (101) surface has been recently reported. The most noticeable difference is that B(OH)(3) and its dimer on the rutile surface have slightly higher binding energies than those on the anatase surface and that the rutile surface is more effective for proton migration from the acid to the surface O-atom.
alpha-MoO(3) nanocrystals of controlled size on a glass substrate
(2009-03-05)
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
A procedure to grow alpha-MoO(3) nanocrystals of rod and belt forms under mild conditions involved deposition onto a glass substrate via vapor transport with a water-soluble precursor. Scanning electron and transmission electron microscopic studies, selected-area electron diffraction and powder X-ray analyses indicate that these alpha-MoO(3) nanocrystals exhibit rod or belt forms that grow along [0 0 1] and became vertically aligned on the glass substrate. Such deposition is effective to form thin films of controllable size and density of coverage on varying the precursor concentration and the duration of deposition. (C) 2008 Published by Elsevier Ltd.
Interfacial reaction between Sn-1Ag-0.5Cu(-Co) solder and Cu substrate with Au/Ni surface finish during reflow reaction
(2009-03-05)
Lin, K. S.
;
Huang, H. Y.
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Chou, C. P.
;
機械工程學系
;
Department of Mechanical Engineering
In order to clarify the effect of the addition of Co to SAC105 solder, the reaction between solder and Au/Ni surface finish has been investigated, and the joint strength was also evaluated by a ball shear test. After soldering, the interfacial reaction layer in the SAC105 Co solder contained Co, and the chemical composition of intermetallic compounds (IMCs) were identified as (Cu,Ni,Co)(6)Sn(5) and (Ni,Cu,Co)(3)Sn(4) by energy-dispersive X-ray spectrometer (EDX), which significantly differed from that of SAC105 solder. After multiple reflows, the formation rate of the (Cu,Ni,Co)(6)Sn(5) IMC for the Co-added solder slow compared with that of (Cu,Ni)(6)Sn(5) IMC for SAC105 solder. Experimental results clearly indicate that adding small amounts (0.05 wt.%) of Co to SAC105 solder strongly affected the formation of the IMC at the interface. Furthermore, ball shear test results demonstrate that the SAC105 and SAC105 Co solder joints have good joint reliability. (C) 2008 Elsevier B.V. All rights reserved.
alpha-MoO3 nanocrystals of controlled size on a glass substrate
(2009-03-05)
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
A procedure to grow alpha-MoO3 nanocrystals of rod and belt forms under mild conditions involved deposition onto a glass substrate via vapor transport with a water-soluble precursor. Scanning electron and transmission electron microscopic studies, selected-area electron diffraction and powder X-ray analyses indicate that these alpha-MoO3 nanocrystals exhibit rod or belt forms that grow along [0 0 1] and became vertically aligned on the glass substrate. Such deposition is effective to form thin films of controllable size and density of coverage on varying the precursor concentration and the duration of deposition. (C) 2008 Published by Elsevier Ltd.
Etching method for nitride semiconductor
(2009-03-05)
Lee, Wei-I
;
Huang, Hsin-Hsiung
;
Zeng, Hung-Yu
The invention discloses etching method for the nitride semiconductor. Firstly dielectric layer is formed on gallium nitride. The line pattern or dot pattern is formed on the dielectric layer by using the exposure, development, and etching processes. The dielectric layer is used as the mask for the epitaxial lateral overgrowth of follow-up gallium nitride layer. The thick gallium nitride film is grown on the dielectric layer. Then the wet etching process is used to remove the dielectric layer, and the thick gallium nitride film on the dielectric layer is etched to form the specific shape as required.
Control of the spatial emission structure of broad-area vertical-cavity surface-emitting lasers by feedback
(2009-03-07)
Schulz-Ruhtenberg, M.
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Tanguy, Y.
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Huang, K. F.
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Jaeger, R.
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Ackemann, T.
The wave number of transverse spatial structures in broad-area vertical-cavity surface-emitting lasers (VCSELs) is controlled via frequency-selective feedback from an external self-imaging cavity in a broad range of wave numbers and emission frequencies. The selected states follow the dispersion curves of the free-running laser. A control range of about 2.5 mu m(-1) in spatial frequency space and 2.5 nm in emission wavelength was obtained for square VCSELs and of about 3 mu m(-1) and 8 nm for circular VCSELs having a different dispersion curve. By spatial filtering in Fourier space, the shape of the structures can also be controlled to some extent. It is argued that the feedback techniques are useful to 'probe' emission states of the free-running laser.
Differential Sensing of Serine and Tyrosine with Aligned CdS Nanowire Arrays Based on pH-Dependent Photoluminescence Behavior
(2009-03-09)
Lin, Yi-Feng
;
Hsu, Yung-Jung
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Cheng, Wei-Yun
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Lu, Shih-Yuan
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材料科學與工程學系
The differential sensing of tyrosine and serine is achieved with well-aligned CdS nanowire arrays by exploring the pH-dependent photoluminescence behavior of the nanowire arrays toward exposure to the two amino acid solutions. The contrasting trend in photoluminescence (PL) intensity with respect to variations in analyte concentration observed at pH 11 served as the check point for the present differential sensing. The application format of the nanowire array is better suited for further sensing device assembly than that of nanocrystal suspensions.
Cobalt nanodots formed by annealing the CoSiO layer for the application of the nonvolatile memory
(2009-03-09)
Hu, Chih-Wei
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Chang, Ting-Chang
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Tu, Chun-Hao
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Shueh, Pei-Kun
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Lin, Chao-Cheng
Co nanodot memory devices formed by oxidation processes were studied. Transmission electron microscopy and x-ray photoelectron spectroscopy analyses showed that overoxidation of the cobalt and silicon degraded the charge-storage ability seriously. However, a precapped oxide can mildly oxidize the CoSi(2) film to protect the overoxidation to occur. In addition, an oxygen-incorporated CoSi(2) film is proposed to improve the oxidation process further. Through incorporating the limited oxygen during sputtering process, the Co nanodot memory device obtains a larger memory window. Also, the reliability characteristic of the Co nanodot memory device formed by annealing the oxygen-incorporated CoSi(2) film has been demonstrated.
Solid State and Solution Self-Assembly of Helical Polypeptides Tethered to Polyhedral Oligomeric Silsesquioxanes
(2009-03-10)
Kuo, Shiao-Wei
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Lee, Hsin-Fang
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Huang, Wu-Jang
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Jeong, Kwang-Un
;
Chang, Feng-Chih
New macromolecular self-assembling building blocks, polyhedral oligo- silsesquioxane (POSS)-helical polypeptide copolymers, have been synthesized through the ring-opening polymerization (ROP) of gamma-benzyl-L-glutamate N-carboxyanhydride (gamma-Bn-Glu NCA) using aminopropyl isobutyl-POSS as a macroinitiator. The incorporation of POSS units at the chain ends of PBLG moieties has two important effects: allowing intramolecular hydrogen bonding between the POSS and PBLG units to enhance the latter's a-helical conformations in the solid state and preventing the aggregation of nanoribbons through the POSS blocks' protrusion from the ribbons to allow the formation of clear gels in solution.
Method for forming a semiconductor structure having nanometer line-width
(2009-03-10)
Chen
;
Szu-Hung
;
Lien
;
Yi-Chung
;
Chang
A method for forming a semiconductor structure having a deep sub-micron or nano scale line-width is disclosed. Structure consisting of multiple photoresist layers is first formed on the substrate, then patterned using adequate exposure energy and development condition so that the bottom photoresist layer is not developed while the first under-cut resist groove is formed on top of the bottom photoresist layer. Anisotropic etching is then performed at a proper angle to the normal of the substrate surface, and a second resist groove is formed by the anisotropic etching. Finally, the metal evaporation process and the lift-off process are carried out and the Γ-shaped metal gate with nano scale line-width can be formed.
Active deformation of Tainan tableland of southwestern Taiwan based on geodetic measurements and SAR interferometry
(2009-03-10)
Huang, Mong-Han
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Hu, Jyr-Ching
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Ching, Kuo-En
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Rau, Ruey-Juin
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Hsieh, Chia-Sheng
The D-InSAR technique is applied to detect the active fault-related folding structure of the Tainan tableland near the deformation front in SW Taiwan by using ERS SAR images during 1996-2000. The Tainan tableland is located in-between a blind fault in the west and the Houchiali fault in the east, thus the Tainan tableland is interpreted as a pop-up structure in a fold-thrust belt at active tectonic margin. Interferometric processing of six SAR images reveals the average slant range deformation (SRD) as similar to 12.5 mm/yr. The uplift rate is higher in eastern Tainan tableland than that in western Tainan tableland, and it increases from west edge of Tainan tableland and decreases across the Houchiali fault. The campaign-mode GPS data set from 1999 to 2003 indicate an average horizontal movement of 12 +/- 4 mm/yr in the direction of N44 degrees W for the Tainan tableland with respect to western coastline. Furthermore 5 precise leveling surveys across Tainan tableland over a period of 2 years show an uplift rate of similar to 14 mm/yr for the benchmarks on the tableland. Based on the 2-D analytical solution with the constraint of he inferred fault geometry, the slip rate along the inferred Tainan fault is similar to 16 mm/yr, similar to 10 mm/yr along the Houchiali fault, and similar to 25 mm/yr along the inferred Chungchou fault. Consequently we propose that active deformation of the Tainan tableland is likely resulted from the freely slipping of the Tainan fault and the Houchiali fault. The locking depth should be located on the deeper part of decollement, eastern of the Chungchou fault. In addition, the combination of D-InSAR, GPS data and the precise leveling data reveals that the short-term deformation rate is larger than long-term deformation rate, which implies that a destructive seismic event could occur in the eastern Tainan area. (c) 2007 Elsevier B.V. All rights reserved.
Effects of seismic anisotropy and geological characteristics on the kinematics of the neighboring Jiufengershan and Hungtsaiping landslides during Chi-Chi earthquake
(2009-03-10)
Dong, Jia-Jyun
;
Lee, Wang-Ru
;
Lin, Ming-Lang
;
Huang, An-Bin
;
Lee, Yen-Liang
The Chi-Chi earthquake (Mw=7.6) of September 21, 1999 triggered many landslides in central Taiwan. Two of these landslides, Hungtsaiping (HTP) and Jiufengershan (JFES) were situated as close as 2 km from each other but had significant differences in their kinematics. JFES landslide was a catastrophic rockslide-avalanche and the HTP landslide was relatively slow-moving. The authors conducted a study to explore the reasons for such differences. Factors such as the characteristics of strong ground motion, sliding direction of landslide, and friction angle of the sliding surface were considered in the study. An analysis of 12 strong-motion records collected in the study area showed that the distribution of horizontal pseudostatic coefficients, earthquake energy ratio and permanent sliding-block displacements (Newmark displacement) were anisotropic with their predominant direction mostly in the E/W-ESE/WNW trending. This direction is perpendicular to the axis of the main geological structures of the studied area. The computed Newmark displacement in the sliding direction of the JFES landslide is larger (44%) than that of the HTP landslide with sliding surface inclination of 21 degrees and friction angle of 28 degrees We can conclude that the seismic anisotropy and the corresponding sliding direction are important contributing factors to the kinematics of studied landslides. The back-calculated friction angle of the sliding surface that corresponds to a critical Newmark displacement for the JFES landslide is about 3.5 degrees higher than that of HTP landslide. The material (colluvium) on the sliding surface in HTP should be less velocity-dependent than that of the JFES landslide (rock) according to the back calculations. The importance of seismic anisotropy, sliding direction, and mechanical properties of sliding surface on the kinematics of deep-seated landslides is demonstrated. (c) 2007 Elsevier B.V. All rights reserved.
A straightforward alpha-selective aromatic glycosylation and its application for stereospecific synthesis of 4-methylumbelliferyl alpha-T-antigen
(2009-03-10)
Chang, Shih-Sheng
;
Lin, Chun-Cheng
;
Li, Yaw-Kuen
;
Mong, Kwok-Kong Tony
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應用化學系
A practical and efficient alpha-selective aromatic glycosylation with simple per-O-acetyl glycopyranosyl trichloroacetimidates is reported. The method is particularly effective for L-fucosyl and 2-azido-2-deoxy-D-galatosaminyl imidates, with which exclusive alpha-selectivity was achieved. The synthetic utility of this method was demonstrated in the stereoselective synthesis of 4-methylumbelliferyl alpha-T-antigen. (C) 2008 Elsevier Ltd. All rights reserved.
Electron transport behavior of individual zinc oxide coated single-walled carbon nanotubes
(2009-03-11)
Lin, Chin-Ching
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Chu, Bryan T. T.
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Tobias, Gerard
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Sahakalkan, Serhat
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Roth, Siegmar
Uniform zinc oxide coated single-walled nanotubes (SWNTs) were fabricated by ultrasonic irradiation with acid-treated SWNTs, zinc acetate, and triethanolamine at low temperature in aqueous phase processing. The ZnO coating process did not decrease the dark current of the SWNTs, but a real decrease in the steady state negative photocurrent was observed after ZnO coating, suggesting a clear photosensitization effect. Transport measurements reveal that the negative photocurrent in s (semiconducting)-SWNTs@ZnO could be described by electron-hole compensation behavior attributed to the ZnO layer under ultraviolet excitation. This simple coating method for one-dimensional material can open up new possibilities for multifunctional nanodevices.
Four-probe electrical-transport measurements on single indium tin oxide nanowires between 1.5 and 300 K
(2009-03-11)
Chiu, Shao-Pin
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Chung, Hui-Fang
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Lin, Yong-Han
;
Kai, Ji-Jung
;
Chen, Fu-Rong
Single-crystalline indium tin oxide (ITO) nanowires (NWs) were grown by the standard thermal evaporation method. The as-grown NWs were typically 100-300 nm in diameter and a few mu m long. Four-probe submicron Ti/Au electrodes on individual NWs were fabricated by the electron-beam lithography technique. The resistivities of several single NWs have been measured from 300 down to 1.5 K. The results indicate that the as-grown ITO NWs are metallic, but disordered. The overall temperature behavior of resistivity can be described by the Bloch-Gruneisen law plus a low-temperature correction due to the scattering of electrons off dynamic point defects. This observation suggests the existence of numerous dynamic point defects in as-grown ITO NWs.
泛用型數位影像防振系統與方法
(2009-03-11)
林進燈
;
徐聖哲
;
梁勝富
本發明提供一種數位影像防振系統與方法,其係利用代表點比對所產生的共相關矩陣以x與y軸最小値投影和倒三角方法計算出局部移動向量可靠性指標,以產生乏條件(ill-conditioned)移動向量,並以背景考慮為基礎,利用對等估算的法則計算出整體移動向量,同時考慮影像平移時可使用的補償向量估算方法,使影像防振可適用於一般靜態或動態的拍攝。因此本發明提供一種數位影像防振系統與方法,係利用有效尋找較可靠之整體移動向量的方法,克服實際影像拍攝中所常面臨的異常情況,並改善傳統的補償方法所造成位置軌跡落後而影響補償效果的問題。