电荷转移络合物对β-胡萝卜素共振拉曼散射截面的影响

利用Vaspec-2048-2紫外光谱仪和Renishaw InVia型共聚焦拉曼光谱仪,测量了极性溶剂1,2-二氯乙烷碘溶液中的β-胡萝卜素的紫外-可见吸收光谱和拉曼光谱.结果表明,生成络合物的β-胡萝卜素在460 nm处的紫外-可见吸收峰消失,并在1000 nm处出现β-胡萝卜素与碘形成络合物的吸收峰,致使514.5 nm激光激发时观察不到络合物中C-C(C—C,C=C)键的共振拉曼光谱.而溶液中没有形成络合物的β-胡萝卜素的C-C键拉曼散射截面减小.其机理为:β-胡萝卜素和碘溶液不稳定,β-胡萝卜素分子结构有序性减弱,导致相干弱阻尼C-C键振动减弱,使得其拉曼散射截面减小.     

魔镜魔镜告诉我

从《白雪公主》中嫉妒心极强的皇后对着镜子说“魔镜魔镜告诉我,谁是世界上最美丽的人”一直到现在,镜子都在人们的生活中扮演着重要的角色。     

光纤共振和预共振喇曼光谱(英)

在液芯光纤内产生共振和预共振喇曼效应，喇曼光谱强度可以大幅度提高，最高可达109倍．本文介绍获得光纤（预）共振喇曼光谱的可行性、实验及实验结果．用远离吸收带的激光激发获得了α甲基吡啶预共振喇曼光谱．用小功率激光（0．8mW）、低浓度溶液（9．6×10(-12)mol／L）还获得了β叶红素在CS2中的共振喇曼光谱．     

Si和Nb对Fe3Al合金基体和缺陷中价电子密度的影响

通过测量二元Fe₃ Al以及含Si或Nb的Fe₃ Al合金的正电子寿命谱参数 ,计算了合金基体和缺陷处的价电子密度 .结果表明 ,Fe₃ Al合金基体的价电子密度较低 ,当Al和Fe结合成Fe₃ Al时 ,Al原子提供价电子与Fe原子的 3d电子形成局域的共价键 .Fe₃ Al合金中金属键和共价键共存 .Fe₃ Al合金晶界缺陷处价电子密度很低 ,键合力较弱 .在Fe₃ Al合金中加入Si,合金基体和晶界处的价电子密度均降低 ,晶内和晶界处的金属键结合力都减弱 .Si的加入使合金变得更脆 .在Fe₃ Al合金中加入Nb降低了合金中的有序度 ,使晶界缺陷处价电子密度升高 ,金属键结合力增强 .但由于Nb的原子半径比Fe大 ,它取代Fe后晶格发生畸变 ,体积增大 ,导致合金基体的价电子密度降低 ,基体的金属键结合力减弱 .     

Land/groove optical recording with GeTe/Sb2Te3 superlattice-like structure

A superlattice-like (SLL) structure was applied to phase-change optical recording. The recording layer consisting of alternating thin layers of two different phase-change materials, GeTe and Sb2Tes, were grown by magnetron sputtering on polycarbonate substrates. Land/groove optical recording was adopted to suppress crosstalk and obtain a large track density. Dynamic properties of the SLL disc were investigated with the shortest 1T pulse duration of 8 ns. Clear eye pattern was observed after 10000 direct overwrite cycles. Erasability above 20 dB was achieved at a constant linear velocity of 19 m/s. Carrier-noise ratio (CNR) kept above 46 dB when the recording frequency reaches 21 MHz. The SLL phase change optical disc demonstrates a better recording performance than the Ge1Sb2Te4 and Ge1Sb4Te7 discs in terms of CNR, erasability, and overwrite jitter.     

RHIC能区Au+Au碰撞中带电粒子直接流与超子整体极化的计算与分析

非对心的相对论重离子碰撞中,不参与碰撞的核子会对参与碰撞的核子产生纵向拖拽,形成一个相对于纵向倾斜的夸克胶子等离子体(QGP)火球.同时,对撞的原子核可将巨大的轨道角动量沉积于QGP中,使其中的部分子沿系统总角动量方向发生自旋极化.在光学Glauber模型基础上,本文构建了倾斜的三维QGP初态条件,并结合3+1维黏滞流体力学模型CLVisc,研究了重离子碰撞的末态带电粒子的直接流和Λ/■超子的整体极化.计算表明,倾斜的初态条件与流体力学模型的结合能够较好地描述RHIC-STAR实验上观测到的直接流与超子整体自旋极化的数据.这为人们利用这些观测量进一步约束重离子碰撞产生的核物质的初始几何与运动学状态提供了理论依据.     

分数阶脉冲半线性微分系统的近似可控性（英文）

本文使用Krasnoselskii's不动点定理、半群理论及分数阶系统理论研究一类分数阶脉冲半线性科学系统的近似可控性,获得该类系统近似可控的充分条件.     

The stimulated Raman scattering competition between solute and solvent in Rhodamine B solution

The competition between the stimulated resonance Raman scattering(SRRS) of Rhodamine B(RhB) and the stimulated Raman scattering(SRS) of ethanol(C2H5OH) is observed at the RhB in C2H5OH solution.For different concentrations of the solution,the peak wavelengths of the SRRS,the amplified spontaneous emission(ASE),the fluorescence and the absorption of RhB are different.The SRRS of RhB and the SRS of C2H5OH are simultaneously generated when the concentration of the solution is 10 5 mol/L and the energy of the excitation laser is 20.4 mJ.Otherwise,only either the SRRS of RhB or the SRS of C2H5OH is generated.The SRRS can be amplified by the ASE gain when the SRRS is near the peak of the ASE,and the peak wavelength of the SRRS coincides with the wavelength of the maximal intensity ASE.     

三角形穿孔翅片对自然对流传热的强化作用

研究一种设置水平矩形翅片对自然对流传热的强化作用,翅片内含三角形穿孔,三角形的底边平行并朝向翅片顶端.比较了这种多孔翅片和同等实心翅片的热耗散率.考虑的参数包括翅片及其穿孔的几何尺寸和热性能.讨论了翅片穿孔后引起的传热强化和翅片重量的减轻.结果表明,在某些三角形穿孔和穿孔间距的值域内,穿孔翅片改进了同等情况实心翅片的热耗散.当翅片导热率及其厚度增大时,穿孔翅片的传热也强化.