Simulations of optical inner-channel thermal deformation for high-power system with unstable resonator

In this letter, the influence on the beam quality due to cumulative effect of the inner channel thermal deformation in the high energy laser system with unstable resonator is researched. Firstly, three typical laser powers of 50, 100, and 150 kW are selected to analyze thermal deformation of mirror by the finite element analyze of thermodynamics instantaneous method. Then the wave front aberration can be calculated by ray-tracing theory. Finally, Strehl ratio and Zernike aberration coefficients of the vacuum far-filed beam can be calculated and comparably analyzed by Fresnel diffraction integration. The theory and simulation results show that due to the effect of inner channel thermal deformation, eccentric phenomenon and astigmatism of far-filed beam emerge, and peak power and the focused ability decrease. With the increasing of reflective times, Strehl ratio decrease, and tilt, astigmatism and coma of x direction gradually increase, which become the main aberration. The results can provide the reference to the thermal aberration analysis for high energy laser system and can be applied to the field of laser nuclear fusion and laser weapon, etc.     

PbBi3低温合金薄膜的制备和超导性质

铋(Bi)和铅(Pb)都是重元素,有很强的自旋-轨道耦合作用,由于原子半径接近,可形成丰富的原子取代合金结构.尽管对高温合金相有了较深入的研究,但对其低温物相的结构和超导物性的认识还很不全面.本文采用低温共沉积和低温退火的方法,在Si(111)-(7×7)衬底上制备了一种基于Bi(110)单晶结构中部分Bi原子被Pb取代的铅铋合金低温相超薄膜新结构,利用扫描隧道显微术(STM)对其结构和电子学性质进行了表征.通过结构表征,确定了合金薄膜表面呈现2^1/2×2^1/2R45°重构的PbBi₃合金相,其母体Bi(110)结构中25%的Bi原子被Pb取代了.通过STM谱学测量,发现合金相PbBi₃为超导相.变温实验表明, PbBi₃相的超导转变温度为6.13 K.在外加垂直磁场下出现的磁通涡旋结构表明PbBi₃薄膜是第Ⅱ类超导体,估算出上临界磁场的下限为0.92 T.测量了由Bi(110)-PbBi₃组成的共面型和台阶型正常金属-超导体异质结中...     

合成引发方式对槲皮素-钴(Ⅱ)配位印迹聚合物结构与性能的影响

以槲皮素-钴(Ⅱ)的配合物为模板分子,在强极性甲醇溶剂中分别采用低温光引发和高温热引发聚合制备槲皮素-钴(Ⅱ)配位印迹聚合物.紫外-可见光谱分析确定了槲皮素与钴(Ⅱ)形成配合物的最佳配位比.根据印迹聚合物的平衡结合量优化功能单体丙烯酰胺用量.利用红外光谱、透射电镜和平衡结合实验,考察不同引发方式对聚合物的结构、微观形貌及结合性能的影响.进一步通过特异吸附容量和印迹指数确定,低温光引发聚合更适于配位分子印迹聚合物的制备.同时研究了不同阳、阴离子对印迹聚合物选择识别性的影响.结果表明光引发的金属配位分子印迹聚合物具有良好的吸附选择性,印迹指数可达3.919.     

氟哌酸分子印迹共混膜的制备及结构表征

以氟哌酸为模板分子,α-甲基丙烯酸为功能单体,三甲氧基丙烷三甲基丙烯酸酯为交联剂,利用本体聚合方法制备了具有特异选择性的氟哌酸分子印迹聚合物,并利用聚砜与氟哌酸分子印迹聚合物共混的方法制备了分子印迹聚合物膜.运用红外光谱分析和透射电子显微镜研究了氟哌酸分子印迹聚合物的结构.运用扫描电子显微镜研究了分子识别膜的机理和吸附性能,运用平衡结合实验法证明了分子识别膜对氟哌酸表现出了较高的选择性.     

锐钛矿型TiO_2(001)-(1×4)表面还原型缺陷对乙醛偶联反应的作用（英文）

本文利用程序升温脱附技术(TPD)研究了乙醛吸附在锐钛矿型TiO_2(001)-(1×4)表面的化学性质.实验结果表明完整晶格位点对乙醛反应表现极为惰性,而表面上的还原型缺陷位点在热驱动下可有效地使乙醛分子通过碳-碳偶联反应生成2-丁酮和丁烯.提出了乙醛在锐钛矿型TiO_2(001)-(1×4)表面偶联反应主要是通过表面还原型缺陷位吸附成对的乙醛分子,因为表面已有的钛原子对还原型缺陷为乙醛分子提供了合适的吸附位点.     

近场动力学与有限元方法耦合求解热传导问题

求解含裂纹等不连续问题一直是计算力学的重点研究课题之一,以偏微分方程为基础的连续介质力学方法处理不连续问题时面临很大的困难.近场动力学方法是一种基于积分方程的非局部理论,在处理不连续问题时有很大的优越性.本文提出了求解含裂纹热传导问题的一种新的近场动力学与有限元法的耦合方法.结合近场动力学方法处理不连续问题的优势以及有限元方法计算效率高的优势,将求解区域划分为两个区域,近场动力学区域和有限元区域.包含裂纹的区域采用近场动力学方法建模,其他区域采用有限元方法建模.本文提出的耦合方案实施简单方便,近场动力学区域与有限元区域之间不需要设置重叠区域.耦合方法通过近场动力学粒子与其域内所有粒子(包括近场动力学粒子和有限元节点)以非局部方式连接,有限元节点与其周围的所有粒子以有限元方式相互作用.将有限元热传导矩阵和近场动力学粒子相互作用矩阵写入同一整体热传导矩阵中,并采用Guyan缩聚法进一步减小计算量.分别采用连续介质力学方法和近场动力学方法对一维以及二维温度场算例进行模拟,结果表明,本文的耦合方法具有较高的计算精度和计算效率.该耦合方案可以进一步拓展到热力耦合条件下含裂纹材料和结构的裂纹扩展问题.     

Correlation function of an optical bistable system with cross-correlated additive white noise and multiplicative colored noise

Considering an optical bistable system with cross-correlated additive white noise and multiplicative colored noise, we study the effects of correlation between the noises on the correlation function C（s） using the unified colored noise approximation and the Stratonovich deeoupling ansatz formalism. The effects of the self-correlation time τ of the multiplicative colored noise and the correlation intensity λ between the two noises are studied with numerical calculation. It is found that C（s） increases with the increase of the self-correlation timeτ, but decreases with the increase of the correlation intensity λ. At large value of τ, there is almost no change for C（s） when τ changes.     

Au(111)表面钴酞菁分子自旋激发态的π电子辅助自旋弛豫

We present our investigation on the spin relaxation of cobalt phthalocyanine (CoPc) films on Au(111) (CoPc/Au(111)) surface using scanning tunneling microscopy and spectroscopy. The spin relaxation time derived from the linewidth of spin-flip inelastic electron tunneling spectroscopy is quantitatively analyzed according to the Korringa-like formula. We find that although this regime of the spin relaxation time calculation by just considering the exchange interaction between itinerant conduction electrons and localized d-shells (s-d exchange interaction) can successfully reproduce the experimental value of the adsorbed magnetic atom, it fails in our case of CoPc/Au(111). Instead, we can obtain the relaxation time that is in good agreement with the experimental result by considering the fact that the π electrons in CoPc molecules are spin polarized, where the spin polarized π electrons extended at the Pc macrocycle may also scatter the conduction electrons in addition to the localized d spins. Our analyses indicate that the scattering by the π electrons provides an efficient spin relaxation channel in addition to the s-d interaction and thus leads to much short relaxation time in such a kind of molecular system on a metal substrate.     

氯吡格雷类似物的合成及其抗血小板聚集活性

α-溴代邻氯苯乙酸经酯化反应后再与4,5,6,7-四氢噻吩并[3,2-c]吡啶发生取代反应合成氯吡格雷类似物(4b～4e);2-(2-氯苯基)-2-(4,5,6,7-四氢噻吩并[3,2-c]吡啶-5-基)乙酸(4a)经酯化反应合成4f～4k;4f与AgNO3反应制得4l;4a经酰胺化制得另外两个氯吡格雷类似物(5c和5m).4和5的其结构经1H NMR,IR和MS表征.初步生物活性测试结果表明:4和5均有一定的抗血小板聚集作用,其中4g和4b尤其突出,对大鼠血小板聚集的抑制百分率分别为46.1%和38.2%.     

微波等离子体法合成SrAl_2O_4:Eu~(2+),Dy~(3+)中激活剂的浓度猝灭研究

采用微波等离子体法合成SrAl_2O_4:Eu~(2+),Dy~(3+)长余辉发光材料,通过对掺杂不同激活剂浓度的产物的光谱性能、余辉性能、相组成结构的分析以及晶胞常数的计算,探讨了微波等离子体法合成srAl_2O_4:Eu~(2+),Dy~(3+)时,激活剂Eu~(2+)的浓度猝灭特性.XRD测试结果表明,Eu~(2+)离子的掺入对基质晶格畸变影响很小;光谱和余辉性能测试表明Eu~(2+)的掺杂浓度对产物的瞬时发光强度影响较大,相对而言对余辉性能的影响程度不大.产物的发光性能随Eu~(2+)摩尔浓度的增大呈现先增强后减弱的趋势,发光中心Eu~(2+)离子的猝灭浓度为4%.结合EDX结果说明,与高温固相法以及其他一些方法相比,采用微波等离子体合成技术可在一定程度上提高Eu~(2+)离子的临界猝灭浓度,从而为进一步提高长余辉发光材料的发光性能提供了可能.