Browsing by Issue Date, starting with "1997-01-07"

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Monte Carlo calculations of the reflection electron energy loss spectra in gold
(1997-01-07)
Kwei, CM
;
Su, P
;
Chen, YF
;
Tung, CJ
;
電子工程學系及電子研究所
The reflection electron energy loss spectra in gold have been calculated using a Monte Carte approach. A description of Monte Carlo simulations based on the dielectric response theory for inelastic volume and surface excitations and the partial wave expansion method for elastic scattering was presented. The influence of surface excitations on the angular and energy spectra of reflected electrons was analysed. These excitations contributed to the energy spectra by single and plural inelastic loss peaks and by the multiple inelastic loss background. Surface plasmons were particularly important for glancing incident or escape electrons. The contribution from surface excitations to the angular spectra was significant for energy losses of a few tenths of an electronvolt but less significant for lower and higher energy losses. The angular spectra revealed single elastic scattering peaks for zero energy loss but flatter multiple elastic scattering curves for large energy losses. In all cases, Monte Carlo simulation results, including surface excitations, agreed very well with experimental data.
Monte Carlo calculations of the reflection electron energy loss spectra in gold
(1997-01-07)
Kwei, CM
;
Su, P
;
Chen, YF
;
Tung, CJ
;
電子工程學系及電子研究所
The reflection electron energy loss spectra in gold have been calculated using a Monte Carte approach. A description of Monte Carlo simulations based on the dielectric response theory for inelastic volume and surface excitations and the partial wave expansion method for elastic scattering was presented. The influence of surface excitations on the angular and energy spectra of reflected electrons was analysed. These excitations contributed to the energy spectra by single and plural inelastic loss peaks and by the multiple inelastic loss background. Surface plasmons were particularly important for glancing incident or escape electrons. The contribution from surface excitations to the angular spectra was significant for energy losses of a few tenths of an electronvolt but less significant for lower and higher energy losses. The angular spectra revealed single elastic scattering peaks for zero energy loss but flatter multiple elastic scattering curves for large energy losses. In all cases, Monte Carlo simulation results, including surface excitations, agreed very well with experimental data.
Molecular conformation and nanomechanics of self-assembled alkylsiloxane monolayers
(1997-01-08)
Huang, JY
;
Song, KJ
;
Lagoutchev, A
;
Yang, PK
;
Chuang, TJ
We have studied the chain conformation and nanomechanical properties of pure alkylsiloxane monolayers and the mixed films with fluorine-containing species using scanning force microscopy (SFM) and infrared-visible sum-frequency generation spectroscopy (IV-SFG). Our IV-SFG spectra yield information about the chain ordering and surface density of specific species in the pure and mixed monolayers. A film formation process involving preferential adsorption of the fluorinated species from solution was observed. On the basis of the SFM measurements, the stiffness of alkylsiloxane monolayers under load was found to increase with the chain length, changes of chain conformation, and alkyl chain fluorination.
Molecular conformation and nanomechanics of self-assembled alkylsiloxane monolayers
(1997-01-08)
Huang, JY
;
Song, KJ
;
Lagoutchev, A
;
Yang, PK
;
Chuang, TJ
We have studied the chain conformation and nanomechanical properties of pure alkylsiloxane monolayers and the mixed films with fluorine-containing species using scanning force microscopy (SFM) and infrared-visible sum-frequency generation spectroscopy (IV-SFG). Our IV-SFG spectra yield information about the chain ordering and surface density of specific species in the pure and mixed monolayers. A film formation process involving preferential adsorption of the fluorinated species from solution was observed. On the basis of the SFM measurements, the stiffness of alkylsiloxane monolayers under load was found to increase with the chain length, changes of chain conformation, and alkyl chain fluorination.
Deposition of polycrystalline beta-SiC films on Si substrates at room temperature
(1997-01-13)
Cheng, KL
;
Cheng, HC
;
Lee, WH
;
Lee, CP
;
Liu, CC
Polycrystalline beta-SiC, with grain size up to 1500 Angstrom, has been room-temperature-deposited on Si substrates by electron cyclotron resonance chemical vapor deposition. Microwave power and the hydrogen carrier gas are the key parameters to lower the deposition temperature. According to the results of the cross-sectional transmission electron microscopy, the grain size appeared to be in the same scale as that deposited at 500 degrees C while a large amount of plasma-induced defects were observed in the Si substrate for the room-temperature-deposited samples. Hence, a CH4-plasma treatment prior to the beta-SiC film growth was adopted, forming a SiC-like interfacial layer to suppress the substrate damages. (C) 1997 American Institute of Physics.
Electrical properties and crystal structure of (Ba,Sr)TiO3 films prepared at low temperatures on a LaNiO3 electrode by radio-frequency magnetron sputtering
(1997-01-13)
Chu, CM
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba,Sr)TiO3 films on a LaNiO3 underlayer were prepared by radio-frequency magnetron sputter deposition. The onset of crystallization of the films occurred at a deposition temperature (T-d) as low as 200 degrees C. Good crystallinity was observed at T-d greater than or equal to 350 degrees C. A moderate high dielectric constant (epsilon(r) similar to 170-250) of the films was obtained at relatively low T-d similar to 200-360 degrees C. The value of epsilon(r) showed a much slower increase with T-d greater than or equal to 350 degrees C than that expected from the progress of crystallinity. The deviation was attributed to an interdiffusion layer formed between the him and underlayer, which also caused an abnormal contact potential barrier and a decline of the epsilon(r) value of the samples postannealed at 350 degrees C. Annealing at 300 degrees C under O-2 atmosphere lessened the oxygen deficiency in the film and enhanced the dielectric constant without forming an interfacial layer. (C) 1997 American Institute of Physics.
Electrical properties and crystal structure of (Ba,Sr)TiO3 films prepared at low temperatures on a LaNiO3 electrode by radio-frequency magnetron sputtering
(1997-01-13)
Chu, CM
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba,Sr)TiO3 films on a LaNiO3 underlayer were prepared by radio-frequency magnetron sputter deposition. The onset of crystallization of the films occurred at a deposition temperature (T-d) as low as 200 degrees C. Good crystallinity was observed at T-d greater than or equal to 350 degrees C. A moderate high dielectric constant (epsilon(r) similar to 170-250) of the films was obtained at relatively low T-d similar to 200-360 degrees C. The value of epsilon(r) showed a much slower increase with T-d greater than or equal to 350 degrees C than that expected from the progress of crystallinity. The deviation was attributed to an interdiffusion layer formed between the him and underlayer, which also caused an abnormal contact potential barrier and a decline of the epsilon(r) value of the samples postannealed at 350 degrees C. Annealing at 300 degrees C under O-2 atmosphere lessened the oxygen deficiency in the film and enhanced the dielectric constant without forming an interfacial layer. (C) 1997 American Institute of Physics.
On-line algorithms for the dominating set problem
(1997-01-14)
King, GH
;
Tzeng, WG
;
資訊工程學系
;
Department of Computer Science
Convergent TCAO close-coupling calculations for electron transfer, excitation and ionization in intermediate keV He2+-H collisions
(1997-01-14)
Kuang, JY
;
Lin, CD
;
物理研究所
;
Institute of Physics
Our recently developed two-centre atomic orbital (TCAO) close-coupling method is applied to He2+-H(1s) collisions in the impact energy range from 20-400 keV amu(-1). Convergent cross sections are obtained for this system by using a large number of bound and pseudostate basis functions on the target and a limited number of bound states on the projectile. Cross sections for electron transfer to 1s, 2l, 3l, 4l and 5l, for excitation to 2l, 3l, 4l and 5l and for ionization are presented and compared with available experimental data and other theoretical calculations. The accuracy of the previous TCAO close-coupling calculations is challenged and the reliability of some experimental data for this system is questioned.
The exact gossiping problem
(1997-01-15)
Tsay, YJ
;
Chang, GJ
;
應用數學系
;
Department of Applied Mathematics
This paper studies a variation of the gossiping problem, where there are n persons, each of whom initially has a message. A pair of persons can pass all messages they have by making one telephone call. The exact gossiping problem is to determine the minimum number of calls for each person to know exactly k messages. This paper gives solution to the problem for k less than or equal to 4 or i + 2(k - i - 2) less than or equal to n less than or equal to i - 2 + 2(k - i - 1) with k/2 - 1 less than or equal to i less than or equal to k - 4.
Passive mode-locking through nonlinear polarization rotation in low-birefringence fibers
(1997-01-15)
Chang, CW
;
Chi, S
;
光電工程學系
;
Department of Photonics
A numerical model for the generation of ultrashort soliton pulses from erbium-doped fiber ring lasers is presented. The model is used to study the pulse dynamics of a simple cavity configuration that uses a low birefringence fiber combined with crossed polarizers. Simulations show that stable pulses with a FWHM as short as 70 fs can be generated. It is also shown that coherent coupling may enhance mode-locking in a weakly linearly birefringent fiber under optimum operation conditions, and in certain cases a period doubling bifurcation occurs due to residual linear birefringence in the fibers.
Polymer dose effects on filtration followed by expression of clay slurries
(1997-01-15)
Chang, IL
;
Chu, CP
;
Lee, DJ
;
Huang, C
;
環境工程研究所
Filtration followed by expression characteristics of cationic polymer conditioned clay slurries are reported for the first time in this work. As the polymer dosage increases, the resistance to filtration greatly decreases until a specific dose has been reached, where the zeta potential is close to zero. And further increase in polymer dose conversely raises the resistance. The expression data are interpreted by the Terzaghi-Voigt combined model, from which the model parameters are evaluated. The polymer conditioning has only a mild effect on the primary consolidation process but has, however, a considerable influence on secondary consolidation characteristics. When zeta potential changes from negative to positive, both the easiness of creeping of constituent particles within the sludge cake and the fraction of moisture removal by the secondary consolidation attain a maximum., The optimal polymer dose criterion considering the filtration and expression stages separately, or in combination, is (sic). (C) 1997 Academic Press
Thickness dependence of refractive index for anodic aluminium oxide films
(1997-01-15)
Chiu, RL
;
Chang, PH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Minimum-maximum exclusive mean (MMEM) filter to remove impulse noise from highly corrupted images
(1997-01-16)
Han, WY
;
Lin, JC
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
The minimum-maximum mean (MMEM) filter is presented to remove impulse noise from highly corrupted images. Simulation results show that even if the occurrence rate of the impulse noise is very high (70%), the restoration performance is still acceptable.
A modified interpolated cell mapping method
(1997-01-16)
Ge, ZM
;
Lee, SC
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A modified interpolated cell mapping (MICM) method is developed for global analysis of deterministic dynamical systems with smooth basin boundaries. By improving the algorithm of the interpolated cell mapping (ICM) and including the idea of sampling mappings of cells from the generalized cell mapping (GCM), MICM gives a more complete and precise global analysis of systems than ICM. In addition, based on analysis using MICM, a method using exact mappings is proposed to remedy the inaccuracy and incompleteness of global analysis due to interpolated mappings and the assumption of the sink cell. For the three systems studied in this paper, this method locates identical attractors and basins of attraction as the integration of a grid of points (IGP) method, with a 100-fold improvement in computational efficiency. (C) 1997 Academic Press Limited.
中國最後一個太監「駕崩」
(1997-01-19)
管領風騷
Quinoxalino-fused sultines and their application in Diels-Alder reactions
(1997-01-21)
Chung, WS
;
Liu, JH
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
The synthesis of 7,8-disubstituted quinoxalino[2,3-d]-[1,2 lambda(4)]oxathiine 2-oxides 7a-c, precursors for quinoxalino-o-quinodimethanes 3a-c, and their application in the Diels-Alder reactions are reported.
正義的怒吼熾熱了愛國的火把
(1997-01-23)
周穂穂
Determination of saikosaponins by micellar electrokinetic capillary chromatography
(1997-01-24)
Hsieh, YZ
;
Huang, HY
;
應用化學系
;
Department of Applied Chemistry
In this study, we examine the feasibility of determining saikosaponins a, b1, b2, c and d, i.e., the bioactive components in Bupleuri Radix, using the micellar electrokinetic capillary chromatography technique. Results obtained from using different anion surfactants, bile salt or sodium dodecyl sulfate (SDS), are also compared. By using bile salt as a pseudostationary phase, the baseline separation of saikosaponins is observed; however, the detection limit is unfavorable. Whereas the baseline resolution of saikosaponins is achieved after adding gamma-cyclodextrin in the SDS running buffer. In addition, another separating method is developed with the mixed micellar system of SDS and Brij 35 containing gamma-cyclodextrin. The contents of saikosaponins in traditional Chinese medicinal prescriptions, such as Sheau Chair Hwu Tang, Bupleuri Radix plant and Chair Hwu San are analyzed by one of the above methods. The entire separation can be completed within 9 min by these methods. The R.S.D. values of the migration times are all below 1%. Moreover, the detection limits of saikosaponins vary from 7 to 33 mu g/ml.
Determination of saikosaponins by micellar electrokinetic capillary chromatography
(1997-01-24)
Hsieh, YZ
;
Huang, HY
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
In this study, we examine the feasibility of determining saikosaponins a, b1, b2, c and d, i.e., the bioactive components in Bupleuri Radix, using the micellar electrokinetic capillary chromatography technique. Results obtained from using different anion surfactants, bile salt or sodium dodecyl sulfate (SDS), are also compared. By using bile salt as a pseudostationary phase, the baseline separation of saikosaponins is observed; however, the detection limit is unfavorable. Whereas the baseline resolution of saikosaponins is achieved after adding gamma-cyclodextrin in the SDS running buffer. In addition, another separating method is developed with the mixed micellar system of SDS and Brij 35 containing gamma-cyclodextrin. The contents of saikosaponins in traditional Chinese medicinal prescriptions, such as Sheau Chair Hwu Tang, Bupleuri Radix plant and Chair Hwu San are analyzed by one of the above methods. The entire separation can be completed within 9 min by these methods. The R.S.D. values of the migration times are all below 1%. Moreover, the detection limits of saikosaponins vary from 7 to 33 mu g/ml.