Investigations on molecular constants of the CD（X^2∏） radical and elastic collisions between ground-state C and D atoms at low temperatures

The potential energy curve of the CD(X~2Π) radical is obtained using the coupled-cluster singles-doublesapproximate-triples [CCSD(T)] theory in combination with the correlation-consistent quintuple basis set augmented with diffuse functions,aug-cc-pV5Z.The potential energy curve is fitted to the Murrell-Sorbie function,which is used to determine the spectroscopic parameters.The obtained D0,De,Re,ωe,ωeχe,αe and Be values are 3.4971 eV,3.6261 eV,0.11197 nm,2097.661 cm 1,34.6963 cm 1,0.2083 cm 1 and 7.7962 cm 1,respectively,which conform almost perfectly to the available measurements.With the potential obtained at the UCCSD(T)/aug-cc-pV5Z level of theory,a total of 24 vibrational states have been predicted for the first time when J = 0 by solving the radial Schr¨odinger equation of nuclear motion.The complete vibrational levels,the classical turning points,the inertial rotation constants and centrifugal distortion constants are reproduced from the CD(X~2Π) potential when J = 0,and are in excellent agreement with the available measurements.The total and the various partial-wave cross sections are calculated for the elastic collisions between the ground-state C and D atoms at energies from 1.0×10 11 to 1.0×10 4 a.u.when the two atoms approach each other along the CD(X~2Π) potential energy curve.Only one shape resonance is found in the total elastic cross sections,and the resonant energy is 8.36×10 6 a.u.The results show that the shape of the total elastic cross section is mainly dominated by the s partial wave at very low temperatures.Because of the weak shape resonances coming from higher partial waves,most of them are passed into oblivion by the strong total elastic cross sections.     

双激光光源光吸收法甲烷浓度光纤监测仪

基于Lamber Beer定律,利用波长为1.33μm的脉冲InP/InGaAsP半导体激光器作为测量光源,用低损耗的光纤进行光信号的传输,并以钽酸锂热释电探测器作为光电转换器件,实现了一种可远距离监测甲烷浓度的仪器。该仪器主要由光纤传感系统、信号放大与处理系统和显示系统三部分组成。介绍了该仪器的基本结构与工作原理,讨论了其中的技术难点及其相应的解决方法。     

Field-free molecular orientation induced by combined femtosecond single- and dual-color laser pulses：The role of delay time and quantum interference

The coherent control of field-free molecular orientation of CO with combined femtosecond single- and dual-color laser pulses has been theoretically studied. The effect of the delay time between the femtosecond single- and dual-color laser pulses is discussed, and the physical mechanism of the enhancement of molecular orientation with pre-alignment of the molecule is investigated. It is found that the basic mechanism is based on the creation of a rotational wave packet by the femtosecond single-color laser pulse. Furthermore, we investigate the interference between multiple rotational excitation pathways following pre-alignment with femtosecond single-color laser pulse. It is shown that such interference can lead to an enhancement of the orientation of CO molecule by a factor of 1.6.     

硅基二维光子晶体耦合器理论研究

光子晶体是一种具有光子带隙的新型人工材料,利用其具有控制和限制光子运动的特性可以制成新颖的光学器件。利用硅基二维光子晶体,提出了一种4端口耦合器。采用时域有限差分法作为研究工具,TM模作为研究对象,从理论上分析了这种器件的特性。在不同的耦合长度下研究光在输出端的功率透射率。结果表明选择适当的耦合长度可以使光在器件中呈现不同的状态。进一步研究表明,通过改变器件内部介质柱的半径,可以改变光在输出端的输出功率。从而证实了这种器件不仅具有波长选择性,而且具有潜在的可调节性,这些特性使得这种器件在全光开关的应用上具有潜在的优势。     

大学物理学(上下册)

正出版社:清华大学出版社简介:中国农业大学新编教材。受益于编者20余年普通物理教学经验,本教材在内容上精心编写,结构合理,难点处理得当,尤其适合于应用技术型本科普通物理课程教学使用。主要有以下四个特点:(1)考虑不同需求,内容划分层次。标有"※"     

Cryptanalysis of an Improved Flexible Ping-Pong Protocol in Perfect and Imperfect Quantum Channels

We recently proposed a flexible quantum secure direct communication protocol [Chin. Phys. Lett. 23 （2006） 3152]. By analyzing its security in the perfect channel from the aspect of quantum information theory, we find that an eavesdropper is capable of stealing all the information without being detected. Two typical attacks are presented to illustrate this point. A solution to this loophole is also suggested and we show its powerfulness against the most general individual attack in the ideal case. We also discuss the security in the imperfect case when there is noise and loss.     

外电场作用下二氧化硅分子的光激发特性研究

采用密度泛函B3P86和组态相互作用方法在6-311G**基组水平上计算了二氧化硅分子从基态到前5个激发态的跃迁波长、振子强度、自发辐射系数A_n0和吸收系数B_0n（n=1—5）.研究了外电场对二氧化硅分子激发态的影响规律. 结果表明,随外电场强度增大,最高占据轨道与最低空轨道能隙变小,占据轨道的电子易于激发至空轨道. 因而在外场作用下分子易于激发. 关键词： 2')" href="#">SiO₂ 激发态 外电场     

基态O和D原子的低能弹性碰撞及OD(X2Π)自由基的准确解析势与分子常数

利用CCSD(T)理论及相关一致五重基aug-cc-pV5Z构建了OD(X2Π)自由基的相互作用势, 计算了这个自由基的光谱常数D0, De, Re, ωe, ωeχe及Be, 其值分别为4.4574,4.6225 eV,0.09702 nm, 2724.923,45.3534和10.0096 cm-1, 均与实验结果相符很好. 利用这一相互作用势, 在绝热近似下通过数值求解双原子分子核运动的径向薛定谔方程, 找到了J=0时OD(X2Π)自由基存在的全部23个振动态, 完整地求出了每一振动态的振动能级、振动经典转折点、惯性转动常数和离心畸变常数, 其值与实验结果相当一致. 在1.0×10-11-1.0×10-3 a.u.的能量范围内研究了基态O和D原子沿OD(X2Π)势能曲线的弹性碰撞, 计算了这一碰撞的总截面和各分波截面, 分析了各分波截面对总截面的不同贡献. 结果表明: 总截面的形状主要由s分波截面决定, 尽管直到l = 12的其他分波截面均有形状共振存在, 但由于其强度较弱, 大都湮没在较强的s分波截面中.     

一种N沟VDMOS电离辐射界面陷阱电流传导性研究

利用X射线对一种N沟VDMOS在不同的负载功率下进行了辐射试验,采用电流-电压(I-V)测试方法发现这种H₂-O₂(氢氧合成)氧化栅介质VDMOS样品存在自退火效应时,新增界面陷阱特性与通常的理论不能够很好地一致.根据所测数据,明确提出了有自退火效应样品的新增界面陷阱除了电荷效应外还具有传导电流能力的观点,初步认为该电流是表面费米能级和陷阱能级相互作用导致的产生复合电流,该电流不能简单地从I-V曲线上定量分 关键词： 界面陷阱 亚阈值电流 X射线辐射 VDMOS     

Properties of Hydrated Alkali Metals Aimed at the Ion Channel Selectivity

The hydration structure properties of different alkali metal ions with eight water molecules and potassium ions with different numbers of water molecules are studied using the mixed density functional theory, B3LYP, with 6-3110 basis set. The hydration structures are obtained from structure optimization and the optimum numbers of water molecules in the innermost hydration shell for the alkali metal ions are found. Some useful information about the ion channel selectivity is presented.