Theoretical Analysis of Interference Nanolithography of Surface Plasmon Polaritons without a Match Layer

Interference nanolithography techniques based on long-range surface plasmon polaritons （LR-SPP） are hardly ever achieved by experiments at present. One key reason is that suitable liquid materials are difflcult to find as the match layer connects the metal film and the resist. We redesign a Kretschmann-Raether structure for interference lithography. A polymer layer is coated under the metal film, and an air layer is placed between the polymer layer and the resist layer. This design not only avoids the above-mentioned question of the match layer, but also can form a soft contact between the polymer layer and the resist layer and can protect the exposure pattern. Simulation results confirm that a device with an appropriately thick polymer layer can form high intensity and contrast interference fringes with a critical dimension of about λ/7 in the resist. In addition, the fabrication of the device is very easy.     

高等学校化学学报第31卷(1～12期)学科分类目次

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改进遗传算法在天然气液化工艺流程优化中的应用

天然气液化工艺流程的设计优化中所涉及的设备、运行参数以及物流的物性参数众多,加之各热力学方程高度非线性这些特点,国内外一些学者将遗传算法这一优秀算法引入到天然气液化流程的优化设计中。但标准遗传算法在天然气液化工艺的优化设计中容易陷入局部最优的陷阱,且收敛的速度及精度还有待提升。本文根据天然气液化工艺优化设计中待优化参数多,耗时长的特点对标准遗传算法进行改进,改进后的遗传算法在提升全局搜索能力的同时还增强了局部搜索能力,对天然气液化流程的优化设计具有很好的适用性。     

可控偏振的量子点光发射

正瑞典研究人员已公布了一项计划,准备制造能发射线性偏振光的量子点。林雪平大学的Anders Lundskog及其同事通过在基部已加长的微型六角形氮化镓金字塔的顶部"种植"量子点,使氮化铟镓量子点所发射的光处于受控状态。他们发现,发射光的偏振方向与基部延长轴是一致的。通过调节氮化铟镓中的铟含量,原则上就可将由量子点发射的光从紫外线波长调到红外线波长。这种方法的好     

Effects of dipole-dipole interaction on entanglement transfer

A system consisting of two different atoms interacting with a two-mode vacuum, where each atom is resonant only with one cavity mode, is considered. The effects of dipole-dipole （dd） interaction between two atoms on the atom-atom entanglement and mode--mode entanglement are investigated. For a weak dd interaction, when the atoms are initially separable, the entanglement between them can be induced by the dd interaction, and the entanglement transfer between the atoms and the modes occurs efficiently; when the atoms are initially entangled, the entanglement transfer is almost not influenced by the dd interaction. However, for a strong dd interaction, it is difficult to transfer the entanglement from the atoms to the modes, but the atom-atom entanglement can be maintained when the atoms are initially entangled.     

Comparison between photoluminescence spectroscopy and photoreflectance spectroscopy in CuGaSe2 epilayer

Photoluminescence （PL） spectroscopy and photoreflectance （PR） spectroscopy are very useful techniques for studying the properties of materials. In this paper, the same material of Cu-rich metal-organic vapour phase epitaxy （MOVPE） grown CuGaSe2 layer is investigated in a temperature range from 20 to 300 K to compare these two techniques. Both PL and PR spectra appear red shifted, less intense and broadened. The temperature dependence of interband transitions is studied by using the Manoogian Leclerc equation. The values of the band gap energy at T=0K and the effective phonon temperature are estimated. The temperature dependences of intensities and broadenings of PL and PR spectral lines are also analysed. Based on the results of the comparison, the features and applications of the PL and PR can be shown in detail.     

Effect of thermal-annealing on the magnetoresistance of manganite-based junctions

Thermal-annealing has been widely used in modulating the oxygen content of manganites. In this work, we have studied the effect of annealing on the transport properties and magnetoresistance of junctions composed of a La0.9Ca0.1MnO3＋6 film and a Nb-doped SrTiO3 substrate. We have demonstrated that the magnetoresistance of junctions is strongly dependent on the annealing conditions： Prom the junction annealed-in-air to the junction annealedin-vacuum, the magnetoresistance near 0-V bias can vary from ～-60% to N～0. A possible mechanism accounting for this phenomenon is discussed.     

Atomistic simulation of kink structure on edge dislocation in bcc iron

Based on the general theory of dislocation and kink, we have constructed the three kink models corresponding to the 1/2 （111）{011} and 1/2 （111）{112} edge dislocations （EDs） in bcc Fe using the molecular dynamics method. We found that the geometric structure of a kink depends on the type of ED and the structural energies of the atom sites in the dislocation core region, as well as the geometric symmetry of the dislocation core and the characteristic of the stacking sequence of atomic plane along the dislocation line. The formation energies and widths of the kinks on the 1/2 （111）{011} and 1/2 （111）{112} EDs are calculated, the formation energies are 0.05eV and 0.04eV, and widths are 6.02b and 6.51b, respectively （b is the magnitude of the Burgers vector）. The small formation energies indicate that the formation of kink in the edge dislocation is very easy in bcc Fe.     

Modelling of spreading process: effect from hydrogen bonds

Lubricant spreading on solid substrates has drawn considerable attention not only for the microscopic wetting theory but also for the dramatic application in head-disk interface of magnetic storage drive systems. Molecular dynamic simulation based on a coarse-grained bead-spring model has been used to study such a spreading process. The spreading profiles indicate that the hydrogen bonds among lubricant molecules and the hydrogen bonds between lubricant molecules and polar atoms of solid substrates will complicate the spreading process in a tremendous degree. The hydrogen bonds among lubricant molecules will strengthen the lubricant combination intensity, which may hinder most molecules from flowing down to the substrates and diffusing along the substrates. And the hydrogen bonds between lubricant molecules and polar atoms of solid substrates will confine the lubricant molecules around polar atoms, which may hinder the molecules from diffusing along the substrates and cause precursor film to vanish.     

Could one single dichotomous noise cause resonant activation for exit time over potential barrier？

This paper studies the mean first passage time （or exit time, or escape time） over the non-fluctuating potential harrier for a system driven only by a dichotomous noise. It finds that the dichotomous noise can make the particles escape over the potential barrier, in some circumstances; but in other circumstances, it can not. In the case that the particles escape over the potential harrier, a resonant activation phenomenon for the mean first passage time over the potential barrier is obtained.