端面抽运四镜折叠腔Nd∶YVO4激光器的研究

基于传输矩阵理论,针对端面抽运的z型折叠腔Nd∶YVO4固体激光器的谐振腔设计进行了数值模拟,详细分析了腔内各参量对谐振腔稳定性的影响.由模拟结果推断,z型腔激光器具有两个稳区,并且稳区的范围可通过谐振腔各分臂的臂长来调节.利用相同的光学元件在不同的稳区范围设计了两种热稳腔,指出了长短腔型各自的利弊.实验考察了输出功率随腔长改变的变化情况,在不同腔长下的不同稳区分别获得了稳定的1 342 nm激光输出,谐振腔稳区范围的变化规律与理论计算基本符合.     

罗丹明B荧光猝灭法测定水中痕量亚氯酸根

在有KI存在的乙酸钠-HCl酸性缓冲溶液中,用520 nm光激发罗丹明B(RhB),在580 nm处有一个荧光峰。当有亚氯酸根(ClO-2)存在时,罗丹明B荧光峰发生猝灭。亚氯酸根浓度在0.021 8～0.51 μg·mL-1范围内与荧光猝灭强度成线性关系,据此建立了一个简便灵敏的亚氯酸根荧光分析新方法,用于测定合成水样中(ClO-₂)的分析,结果令人满意。     

通讯波段单光子探测器的研制

将InGaAs/InP雪崩光电二极管应用于盖革模式下,采用门脉冲模式淬灭雪崩,并使用魔T混合网络抑制尖峰噪声,实现了通信波段1550 nm的单光子探测.在APD工作温度为223 K时,测得暗计数率与探测效率的比值为0.035.     

振动波包法模拟氢溴酸光解离动力学

研究了在零度和非零度时的双原子分子离子HBr⁺在不同包络函数的超快激光脉冲作用下的光解离动力学. 主要计算了HBr⁺电子基态时的参数. 利用从头算理论在CCSD/6-311++G(3df,2pd)水平计算了HBr+的势能值,用Morse参数模拟后,与非依时傅立叶格点哈密顿方法获得的束缚态振动能量本征值进行比较. 另外,探索了温度、脉冲包络函数和光强度对光解离过程的影响.     

利用BSO晶体的电控自聚焦效应实现的一种新型电光调制

BSO(硅酸铋)晶体除了具有热自聚焦效应外¹,还具有电控自聚焦效应²,基于电控自聚焦效应,又进一步对高斯光束经BSO晶体自聚焦后的远场光斑中心处的光强与加在晶体通光方向上的电压和入射光功率的关系进行了理论和实验研究,提出一种新的电光调制方法。理论与实验相符,进一步验证了文献1、2的结论.     

Characterization and chemical behavior of submonolayer coverages of titania on a Pt foil

The interaction between submonolayer titania coverages and Pt foil has been studied by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). The submonolayer titania can be fully oxidized to TiO₂ at 923 K under 10⁻⁸ Torr O₂, and partially oxidized to TiO_x at lower oxidation temperatures. The oxidized surface can be reduced by annealing to 1000 K or higher, or by heating in H₂ at 823 K, or by interacting with surface carbon formed from acetone decomposition. Under certain conditions (e.g., hydrogen reduction at 923 K), the surface titania can be fully reduced to metallic Ti which diffuses into bulk Pt readily. The reduced metallic Ti can resurface when the surface is oxidized at 923 K. Both XPS and HREELS data indicate the existence of subsurface oxygen, which plays an important role for the diffusion of Ti into and out of the Pt foil. Although no special interfacial active sites were revealed by HREELS studies of adsorbed acetone and CO, some TPD and XPS data suggest the presence of sites active for acetone decomposition.     

Dy3+含量对Eu2+,Dy3+共掺高硅氧发光玻璃发光性能的影响

通过控制Dy3+的掺杂浓度,制备出了不同浓度的Eu2+,Dy3+单掺和共掺高硅氧发光玻璃,测试其激发和发射光谱,讨论了Dy3+浓度对Eu2+,Dy3+共掺样品发光性质的影响。结果表明,Eu2+,Dy3+共掺高硅氧发光玻璃中存在Dy3+向Eu2+的无辐射能量传递现象,且Dy3+的引入会使高硅氧发光玻璃中Eu—O的共价作用减弱,造成Eu2+发射峰蓝移;随着Dy3+浓度的增加,Dy3+→Eu2+能量传递增强,Eu2+发光增强;Dy3+含量继续增加,则Dy3+发光出现浓度猝灭,且Dy3+→Eu2+能量传递减弱。     

Cd(Ⅲ)、Co(Ⅲ)、Cu(Ⅲ)与异烟酸的配合物合成与性质

以异烟酸为配体合成了Cd(Ⅱ)、Co(Ⅱ)、Cu(Ⅱ)3种配合物,用X-射线单晶衍射研究了其结构,3种配合物具有类似的六配位结构,由于Jahn-Teller效应使Cu(Ⅱ)的配合物的结构为一伸长的八面体;3个配合物的配位原子均为4个水分子的氧原子和两个异烟酸根的氮原子,羧基仅参与形成氢键。对配合物的热稳定性进行了研究,并对Cd(Ⅱ)配合物非等温热分解动力学方程和动力学参数进行了拟合,结果表明动力学补偿效应方程与数据拟合方法无关。     

基于主成分回归的温度分布反演研究

多谱辐射测温是一种非接触温度测量方法,目前常用的多谱辐射测温只能反演出一个近似温度值,而无法给出实际的温度分布。针对此问题,基于普朗克定律,采用主成分回归算法,以强激光毁伤靶材温度测量为例,在脉冲能量为34.2 J的激光入射条件下,从热辐射谱中反演出近似温度值为2 700 K,拟合相对偏差为0.5%,当温度分布范围为2 600～2 800 K时,拟合相对偏差减小为0.13%,减小了温度反演偏差。首次给出了基于主成分回归方法的温度分布反演,提高了非接触式温度测量的表征精度。     

Multifractal properties of denaturation process based on Peyrard–Bishop model

DNA has attracted the interest of physicists for a long time. One interesting theoretical question is its melting behavior. The Rényi dimension spectrum of the melting transition of DNA, reveals the multifractal nature of the dynamics of the Peyrard–Bishop model. In this Letter, the effects of different parameters involved in the Peyrard–Bishop model on the multifractal nature of the melting dynamics of a DNA chain are investigated in details. As a result, it can be concluded that not only the best multifractality nature of the model arises from the Morse potential term which is taken in the model but also the multifractal nature of the model is independent of the homogeneity, the length of chain, stacking terms, the thermal bath simulation methods and even the potentials which describe the interaction between the two bases in a pair. Furthermore, our results confirm that, the best potential to describe the interactions between the bases in pairs in the PB and PBD models is the Morse potential.