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41.
Jung-Hui Tsai Shao-Yen Chiu Wen-Shiung Lour Wen-Chau Liu Chien-Ming Li Ning-Xing Su Yi-Zhen Wu Yin-Shan Huang 《Superlattices and Microstructures》2009
In this paper, the device performance and complementary inverter of the InGaP/InGaAs/GaAs doped-channel field-effect transistors (DCFETs) by two-dimensional semiconductor simulation are demonstrated. Due to the relatively large conduction (valance) band discontinuity at InGaP/InGaAs interface, it provides good confinement effect for transporting carriers in InGaAs channel layer for the n-channel (p-channel) device. The large gate turn-on voltage is achieved due to the employment of the wide energy-gap InGaP material as gate layer. The ft and fmax are of 6.5 (2.1) and 25 (5) GHz for the n-channel (p-channel) device. Furthermore, the co-integrated structures, by the combination of n- and p-channel field-effect transistors, could form a complementary inverter and the relatively large noise margins are achieved. 相似文献
42.
A detailed computational study has been performed at the QCISD(T)/6-311++G(d,p)//B3LYP/6-311++G(d,p) level for the NCO with CH3 reaction by constructing singlet and triplet potential energy surfaces (PES). The results show that the title reaction is more favorable for the singlet PES than the triplet PES. On the singlet PES, the dominant channel is the barrierless addition of the O or N atom to the C atom of the methyl group to form CH3NCO (IM1) and CH3OCN (IM2). On the triplet PES, the favorable channel is the barrierless addition of the N atom to the C atom of the methyl group to form an intermediate CH3NCO (3IM2), which then undergoes a N–C bond scission process to give out CH3N + CO. 相似文献
43.
Hu YZ Wilson MH Zong R Bonnefous C McMillin DR Thummel RP 《Dalton transactions (Cambridge, England : 2003)》2005,(2):354-358
The ligand 2-(8'-quinolinyl)-1,10-phenanthroline (1) was prepared in 79% yield by the Friedlander condensation of 8-amino-7-quinolinecarbaldehyde and 8-acetylquinoline. The complex [Pt(1)Cl]+ was prepared and compared with the isomeric 2-(2'-quinolinyl)-1,10-phenanthroline (2) complex. An X-ray analysis indicated that the six-membered chelate ring in the tridentate complex resulted in a relief of angle strain as well as some non-planarity in the bound ligand 1. The control system for photophysical studies is [Pt3Cl]+ where denotes 2-(2'-pyridyl)-1,10-phenanthroline. Relative to the complex of 3, in dichloromethane solution [Pt(1)Cl]+ exhibits noticeably higher energy charge-transfer absorption but slightly lower energy emission. The gap between the onset of absorption and emission is larger because the emission from [Pt(1)Cl]+ originates from a triplet excited state with substantial intra-ligand character. At room temperature in deoxygenated dichloromethane, [Pt(1)Cl]+ has an excited-state lifetime of 310 ns vs. 230 ns for [Pt(1)Cl]+. Within the series, [Pt(1)Cl]+ also exhibits the largest activation barrier for thermally induced quenching at 2730 cm(-1) in fluid dichloromethane solution. However, the barrier is only about 50% larger than that found for [Pt(1)Cl]+. There is reduced ring strain in [Pt(1)Cl]+, but inter-ligand steric interactions weaken the ligand field. 相似文献
44.
A series of four biphen (phen = 1,10-phenanthroline) ligands, 2,2'-biphen (1), 3,3'-biphen (2), 2,2'-dimethylene-3,3'-biphen (3), and 2,3'-dimethylene-3,2'-biphen (4), is prepared by coupling and Friedl?nder methodology. The corresponding mononuclear Ru(II) complexes, [Ru(1-4)(Mebpy)(2)](2+) where Mebpy = 4,4'-dimethyl-2,2'-bipyridine, are prepared. These complexes show long wavelength electronic absorptions at 441-452 nm and emissions at 622-641 nm. Metal-based oxidations occur in the range 1.18-1.21 V, and ligand-based reductions, at -1.20 to -1.30 V. The addition of Zn(2+), Cd(2+), or Hg(2+) ions results in a strong enhancement and red shift of the luminescence of complex Ru-3. Alkali and alkaline earth metal ions barely affect the luminescence of Ru-3 while transition metal ions such as Co(2+), Cu(2+), Ni(2+), and Mn(2+) lead to efficient quenching of the Ru-3 luminescence. The luminescence of Ru-2 and Ru-4 is quenched in the presence of Zn(2+) because of a conformationally induced reduction in electronic communication between the two phen halves of the ligand. The addition of Zn(2+) has only a slight effect on the luminescence of Ru-1 because of steric hindrance toward complexation. 相似文献
45.
Experimental investigations based on our custom-built torsion resonator were carried out on the kinetics and relaxation of the structural formation process in three agar–water solutions with agar concentrations of 0.75, 1.0, and 2.0 % w/w under natural cooling. An interesting temperature-dependent oscillatory decaying behavior of the structure development rate (SDR) in the agar gelation process is observed. This oscillatory SDR-decaying behavior is indicative of a sum of multiple SDR-determining relaxation processes and could be quantitatively described by a multiple-order Gaussian-like equation, i.e., $dG^{\prime }/dt\equiv \sum \nolimits _{n=0}^{m}{dG^{\prime }/dt}^{(n)}=\sum \nolimits _{n=0}^{m}K_{n}{\rm exp}[-2(T-T_{n})^{2}/W_{n}^{2}]$ . The ${\rm T}_{n}$ dependences of ${\rm W}_{n}$ in the gelation zone were also found to follow the Arrhenius law with activation energies of 39–74 kJ/mol for three investigated samples, indicating the important role of formation or fission of the hydrogen bonding interaction playing in the agar structural network formation. These findings provide insights into the mechanical properties and distinctive structure development rates of agar sols that dynamically and naturally evolve to form gels. 相似文献
46.
SHENG Li-Na SONG Ming-Tao ZHANG Xiao-Qi YANG Xiao-Tian GAO Da-Qing HE Yuan ZHANG Bin LIU Jie SUN You-Mei DANG Bing-Rong LI Wen-Jian SU Hong MAN Kai-Di GUO Yi-Zhen WANG Zhi-Guang ZHAN Wen-Long 《中国物理C(英文版)》2009,33(4):315-320
A state-of-the-art high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics of the Chinese Academy of Sciences. This microbeam system operates in both full current intensity mode and single ion mode. It delivers a predefined number of ions to pre-selected targets for research in biology and material science. The characteristic of this microbeam system is high energy and vertical irradiation. A quadrupole focusing system, in combination with a series of slits, has been designed to optimize the spatial resolution. A symmetrically achromatic system leads the beam downwards and serves simulta-neously as an energy analyzer. A high gradient quadrupole triplet finally focuses a C6+ ion beam to 1 μm in the vacuum chamber within the energy range from 10 MeV/u to 100 MeV/u. In this paper, the IMP microbeam system is described in detail. A systematic investigation of the ion beam optics of this microbeam system is presented together with the associated aberrations. Comparison is made between the IMP microbeam system and the other existing systems to further discuss the performance of this microbeam. Then the optimized initial beam parameters are given for high resolution and high hitting efficiency. At last, the experiment platform is briefly introduced. 相似文献
47.
Non-Contact to Contact Transition: Direct Measurements of Interaction Forces between a Solid Probe and a Planar Air-Water Interface 下载免费PDF全文
The interaction force between a solid probe and a planar air-water interface is measured by using an atomic force microscope. It is demonstrated that during the approach of the probe to the air-water interface, the force curves decline all the time due to the van der Waals attraction and induces a stable profile of water surface raised. When the tip approaches very close to the water surface, force curves jump suddenly, reflecting the complex behaviour of the unstable water surface. With a theoretical analysis we conclude that before the tip touches water surface, two water profiles appear, one stable and the other unstable. Then, with further approaching, the tip touches water surface and the non-contact to contact transition occurs. 相似文献
48.
The potential energy surface for the reaction of CH3S with CO was calculated at the G3MP2//B3LYP/6-311++G(d,p) level. The rate constants for feasible channels leading to several products were calculated by TST and multichannel-RRKM theory. The results show that addition–elimination mechanism is dominant, while hydrogen abstraction mechanism is uncompetitive. The major channel is the addition of CO to CH3S leading to an intermediate CH3SCO which then decomposes to CH3 + OCS. In the temperature range of 200–3000 K, the overall rate constants are positive temperature dependence and pressure independence, and it can be described by the expression as k = 1.10 × 10−16T1.57exp(−3359/T) cm3 molecule−1 s−1. At temperature between 208 and 295 K, the calculated rate constants are in good agreement with the experimental upper limit data. At T = 1000 and 2000 K, the major product is CH3 + OCS at lower pressure; while at higher pressure, the stabilization of IM1 is dominant channel. 相似文献
49.
Jing-Yu Sun Yi-Zhen Tang Hao Sun Xiu-Juan Jia Xiu-Mei Pan Ya-Ru Pan Rong-Shun Wang 《Theoretical chemistry accounts》2008,121(1-2):33-41
A detailed computational study has been performed on the mechanism and kinetics of the C2H + CH3CN reaction. The geometries were optimized at the BHandHLYP/6–311G(d, p) level. The single-point energies were calculated using the BMC-CCSD, MC-QCISD and QCISD(T)/6–311+G(2df, 2pd) methods. Five mechanisms were investigated, namely, direct hydrogen abstraction, C-addition/elimination, N-addition/elimination, C2H–to–CN substitution and H-migration. The kinetics of the title reaction were studied using TST and multichannel RRKM methodologies over a wide range of temperatures (150–3,000 K) and pressures (10?4–104 torr). The total rate constants show positive temperature dependence and pressure independence. At lower temperatures, the C-addition step is the most feasible channel to produce CH3 and HCCCN. At higher temperatures, the direct hydrogen abstraction path is the dominant channel leading to C2H2 and CH2CN. The calculated overall rate constants are in good agreement with the experimental data. 相似文献
50.
Yi-Zhen Tang Ya-Ru Pan Jing-Yu Sun Hao Sun Rong-Shun Wang 《Theoretical chemistry accounts》2008,121(3-4):201-207
The mechanism for the CH2SH + O2 reaction was investigated by DFT and ab initio chemistry methods. The geometries of all possible stationary points were optimized at the B3LYP/6-311+G(d,p) level, and the single point energy was calculated at the CCSD(T)/cc-pVXZ(X = D and T), G3MP2 and BMC-CCSD levels. The results indicate that the oxidation of CH2SH by O2 to form HSCH2OO is a barrierless process. The most favorable channel is the rearrangement of the initial adduct HSCH2OO (IM1) to form another intermediate H2C(S)OOH (IM3) via a five-center transition state, and then the C–O bond fission in IM3 leads to a complex CH2S. . .HO2 (MC1), which finally gives out to the major product CH2S + HO2. Due to high barriers, other products including cis- and trans-HC(O)SH + HO could be negligible. The direct abstraction channel was also determined to yield CH2S + HO2, with the barrier height of 22.3, 18.1 and 15.0 kcal/mol at G3MP2, CCSD(T)/cc-pVTZ and BMC-CCSD levels, respectively, it is not competitive with the addition channel, in which all stationary points are lower than reactant energetically. The other channels to produce cis- and trans-CHSH + HO2 are also of no importance. 相似文献