Local Density of States Modulated by Strain in Marginally Twisted Bilayer Graphene

In marginally twisted bilayer graphene, the Moiré pattern consists of the maximized AB(BA) stacking regions,minimized AA stacking regions and triangular networks of domain walls. Here we realize the strain-modulated electronic structures of marginally twisted bilayer graphene by scanning tunneling microscopy/spectroscopy and density functional theory(DFT) calculations. The experimental data show four peaks near the Fermi energy at the AA regions. DFT calculations indicate that the two new peaks ...     

Three—Wave Resonant Interactions in Self—Defocusing Optical Media

A three-wave resonant interaction for nonlinear excitations created from a continuous-wave background is shownto be possible in an isotropic optical medium with a self-defocusing cubic nonlinearity. Under suitable phase-matching conditions the nonlinear envelope equations for the resonant interaction are derived by using a methodof multiple-scales. Some explicit three-wave solitary wave and lump solutions are discussed.     

Fibonacci光栅衍射频谱的自相似结构

本文设计并制作了一种按Ｆｉｂｏｎａｃｃｉ数列规则排列的准周期衍射光栅，从理论和实验两方面计算与显示了该光栅的自相似衍射频谱，这对准晶体光学中非周期的频率分析研究有一定的理论和实用价值。     

SOLITON EXCITATIONS INA DIATOMIC LATTICE WITH NONLINEAR ON-SITE POTENTIAL

We consider the soliton excitations in a diatomic chain with nonlinear on-site potential based on a quell-discreteness approximation, Different from the theoretical approach devel-oped before, our method is valid in the whole Brillouin zone of phonons. The gap solitons observed recently in a nonlinear diatomic pendulum lattice can be well explained qualita-tively. It is also shown that if the wave number of the carrier wave is near the edge of the Brillouin zone, the results coinside with that of Kivshar and Flytzanis about the gap solitons in diatomic lattices when the difference of mass between two kinds of atoms becomes small.     

(NH3CH2CHNH2CH3)2[WVIO2(OC6H4O)2]的合成、晶体结构及其与ATP相互作用的NMR性质研究

在室温下, 选用具有手性特征的1,2-丙二胺(1,2-propanediamine)为对阳离子, 由正四丁基铵十钨酸盐和邻苯二酚反应, 得到了钨酶活性结构因子仿生配合物(NH3CH2CHNH2CH3)2[WVIO2(OC6H4O)2], 用单晶X射线衍射测定了其晶体结构, 晶体属单斜晶系, 空间群为P21/n, a＝1.1099(3) nm, b＝1.0416(3) nm, c＝1.8874(6) nm, β＝96.492(6)°, V＝2.1679(11) nm3, z＝4, R1＝0.0445, wR2＝0.0682; 并对它进行了IR, 1H NMR和UV-Vis谱学表征. 利用NMR研究了其与三磷酸腺苷(ATP)的相互作用, 结果发现手性特征的1,2-丙二胺及邻苯二酚苯环的1H化学位移在与ATP混合前后均呈现出较大的差异, 分析得出: 配合物中的金属离子在D2O中大多数均以W(V)价态存在, 但在与ATP共存时转化为W(VI), 并与配体发生了解离.     

Landau Damping of Collective Modes in a Disc-Shaped Bose-Einstein Condensate

We investigate the Landau damping of collective modes in an anisotropic Bose Einstein condensate （BEC）, Based on divergence-free analytical solutions for the ground state wavefunction of the condensate and all eigenvalues and eigenfunctions for thermal excited quasiparticles, we make a detailed analytical calculation on coupling matrix elements. We evaluate the Landau damping of a quadrupole collective mode in the BEC with a disc-shaped trap and discuss its dependence on temperature and particle number of the system.     

具有二阶和三阶非线性一维光子晶体中的耦合模孤子

研究同时具有二阶和三阶非线性的一维光子晶体中的耦合孤子动力学. 从Maxwell方程出发,利用多重尺度法,导出了光学整流场与两个基频电场包络的非线性耦合模方程组,给出了耦合模方程组的孤子解. 结果表明,由于二阶非线性导致的光学整流场对基频电场有调制作用,使得两个基频电场分量可以呈现为亮孤子-亮孤子、暗孤子-暗孤子及亮孤子-暗孤子对;当两个基频电场的振动频率趋于光子晶体频带的带边频率时,光学整流场消失.     

闪耀光栅的傅里叶分析

用傅里叶光学来解决周期性结构的衍射问题既准确方便又容易理解。从研究透射闪耀光栅的透射函数及反射闪耀光栅的反射函数出发 ,利用傅里叶光学原理 ,从理论上分析了闪耀光栅衍射图样的复振幅和光强分布与闪耀角及波长的关系 ,并利用计算机进行了模拟计算。计算的效率曲线与实际刻划的闪耀光栅效率曲线吻合的很好。