硅甲烷CARS光谱的研究

测量和分析了硅甲烷(SiH_4)v_1带和v_3带的CARS光谱,并采用偏振CARS技术,解除了v_1带的影响,获得了完全的v_3带的CARS谱.偏振测量和理论模拟计算给出了v_1带和v_3带Q支峰值间的频率位移及两者喇曼跃迁截面平方的比值.     

CH_3CN分子ν_1,ν_4,ν_5,ν_7和ν_2+ν_4带的高分辨付里叶变换红外光谱研究

利用分辨率为0.06cm~(-1)的付里叶变换光谱技术研究了CH_3CN分子的v_1,v_4,v_5,v_7和v_2+v_4五个带。观察到了六百多条谱线,并利用最小二乘方方法对这些线进行了拟合,得到了一些新的分子常数。原有的常数也得到了很大的改进。     

水汽分子碰撞加宽的理论研究

本文利用考虑短程强相互作用势、电四极矩_(H_2O)—电四极矩_(N_2)和电偶极矩_(H_2O)—电四极矩_(N_2)—相互作用的QFT理论(以下简称为QFT~*理论),计算了水汽分子纯转动带和_(v_2)振动带谱线的碰撞加宽线宽,以及v_(_2)振动带谱线线宽的温度依赖关系。结果表明:①利用QFT~*方法的计算值比Gamache等人的理论计算值更接近于实验值。③在计算水汽分子吸收谱线的氮分子碰撞加宽时,短程强相互作用势的影响是十分重要的,而电四极矩_(H_2O)—电四极矩_(N_2)相互作用的影响在任何情况下都是不大的,其贡献仅为1%左右。②压力加宽线宽的温度依赖关系是十分复杂的,字不仅与J有关,而且还与K_α有关。     

氯化铀酰—焦磷酸四钠溶液的拉曼光谱研究

本文用激光拉曼光谱法研究了焦磷酸四钠溶液、氯化铀酰溶液、氯化汞溶液和氯化铀酰-焦磷酸四钠溶液,解释了焦磷酸铀酞络合物的荧光辐射机理、v_(?)(U—O)红移效应和v_s(PO_2)、v_5(P—O—P)、v_s(P—O—P)紫移效应。     

用可调谐二极管激光光谱仪观测3657—3708cm~(-1)区域CO_2高分辨振转光谱

用可调谐二极管激光光谱仪观测到3657—3708cm~(-1)区域内CO_2各种同位素分子的9个振转谱带。首次观测到~(12)C~(16)O~(17)O的10011—00001谱带和~(12)C~(16)O~(18)O的11111—01101谱带,对其余7个谱带则扩充了其观测振转线的数目。用最小二乘方拟合法计算了各谱带的光谱常数,发现CO_2分子常数表中~(12)C~(16)O~(17)O的10011—00001谱带中心v的计算值比本实验观测值大0.287cm~(-1),而~(12)C~(16)O~(12)O的11111—01101谱带中心v_0的计算值则比本实验观测值小0.048cm~(-1)。     

烃类混合物的McAllister三体模型通用化

McAllister三体模型的关联性限制了其拓展应用,本文在搜集文献中14类系列型烃类混合物黏度实验数据的基础上,拟合得到了其模型参数。分析发现,McAllister三体模型的两个待定参数(v_(12)与v_(21))与等效沸点(T_(bij))及实验温度(T)间存在一定的规律,由此获得了模型参数的定量推算关系,进而建立了一种具有预测同系列烃类混合物黏度的通用化McAllister三体模型。将新模型的计算结果与实验值进行比较表明,对于所有二元体系的总体平均相对偏差为0.79%,最大相对偏差为7.22%。     

乙炔(2v_5-v5)、(v_4+v_5)-v_4和(2v_4-v_5)_I-2v_4Q—支高分辨二极管激光光谱

用高分辨二极管激光光谱仪对乙炔v_5区域的几个Q支作了研究.在725cm~(-1)附近观察到(2v_4+v_5)I-2v_4的Q支.并对(2v_5-v_5)和(v_4+v_5)-v_4的Q支进行了观察.观测到一些微扰现象.对观测到的谱线利用最小二乘法进行了拟合,得到了部分分子常数.     

He-H_2S复合物的六维从头算势能面和束缚态（英文）

采用[CCSD(T)]-F12a/aug-cc-pVTZ方法,同时在基组中引入中心键函数(3s3p2d1f1g)构建了He-H_2S复合物的高精度六维势能面.除分子间振动坐标,同时考虑了H_2S分子内的v_1对称伸缩振动Q_1正则模、v_2弯曲振动Q_2正则模和v_3反对称伸缩振动Q_3正则模三种振动模式.将计算得到的六维势能面在Q_1,Q_2和Q_3方向上分别做积分得到H_2S单体分别处于振动基态、v_2和v_3激发态下的He-H_2S的三个振动平均势能面.计算结果表明,每个平均势能面都有一个T形全局极小值、一个平面局部极小值、两个平面内鞍点和一个平面外鞍点.全局极小值的几何构型位于R=3.46 A,θ=109.9~°和_(φ=)0.0°,势阱深度为35.301 cm-1.在径向部分采用离散变量表象法和角度部分采用有限基组表象法并结合Lanczos循环算法计算了He-H_2S的振转能级和束缚态.计算发现He-(par a-H_2S)在H_2S的_(v_2)和v_3区域的带心位移分别为0.025 cm~(-1)和0.031 cm~(-1),而He-(ortho-H_2S)的带心位移分别为0.041 cm~(-1)和0.060 cm~(-1),都表现为蓝移.     

三氧化钨表面氢吸附机理的第一性原理研究

采用基于密度泛函理论的第一性原理平面波超软赝势方法,在广义梯度近似下,研究了立方WO_3,WO_3(001)表面结构及其氢吸附机理.计算结果表明立方晶体WO_3理论带隙宽度为0.587 eV.WO_3(001)表面有WO终止(001)表面和O终止(001)表面两种结构,表面结构优化后W—O键长和W—O—W键角改变,从而实现表面弛豫;WO终止(001)表面和O终止(001)表面分别呈现n型半导体特征和p型半导体特征.分别计算了H原子吸附在WO终止(001)表面和O终止(001)表面的H—O_(2c)—H,H—O_(2c)…H—O_(2c),H—O_(1c)—H和H—O_(1c)…H—O_(1c)四种吸附构型,其中H—O_(1c)—H吸附构型的吸附能最小,H—O键最短,H失去电子数最多,分别为-3.684 eV,0.0968 nm和0.55e,此吸附构型最稳定.分析其吸附前后的态密度,带隙从吸附前的0.624 eV增加到1.004 eV,价带宽度基本不变.H的1s轨道电子与O的2p,2s轨道电子相互作用,在-8和-20 eV附近各形成了一个较强的孤立电子峰,两个H原子分别与一个O_(1c)原子形成化学键,最终吸附反应生成了一个H_2O分子,同时产生了一个表面氧空位.     

CH2Cl2分子中CH的摇摆振动与伸缩和弯曲振动的耦合

用傅立叶变换光谱仪和光学长程装置,记录了CH_2Cl_2分子振动量子数v=1～4的红外吸收光谱(1200～12000 cm~(-1)),归属出CH的伸缩(v_1,v_6)振动和弯曲(v_2)振动和CH_2基团相对于CCl_2基团的摇摆振动(v_8)的泛频和合频能级共47个。考虑了摇摆振动与伸缩和弯曲振动的耦合,使用简正模模型对v_1,v_2,v_6和v_8这四种振动模式的泛频和合频能级进行了拟合,得到了非谐性常数和费米(Fermi)共振和达宁-丹尼生(Darling-Dennison)共振系数。结果表明,摇摆振动与伸缩振动之间的Fermi共振(k_(188)=-254.63 cm~(-1))大于弯曲振动与伸缩振动之间的Fermi共振(k_(122)=-54.87 cm~(-1))；伸缩振动之间的Darling-Dennison共振(k_(1166)=-215.28 cm~(-1))大于弯曲振动与摇摆振动之间的Darling-Dennison共振(k_(2288)=-5.72 cm~(-1))。用拟合得到的光谱参数计算出CH_2Cl_2分子的振动能级,与实验数据很好地符合。     

Speckle characteristics of a broad-area VCSEL in the incoherent emission regime

We present a technique to reduce the speckle contrast of a NIR broad-area VCSEL based on the spatially incoherent emission regime that can be obtained when using the proper driving conditions. We evaluate the efficiency of this technique to reduce the speckle contrast by comparing it with the speckle characteristics in multimode emission under cw operation. Depending on the illumination setup, the incoherent emission regime can lead to a strongly reduced speckle contrast down to 1.3%. This is in agreement with estimates of the expected speckle contrast reduction when three contrast reducing effects are taken into account. These low contrast values make the investigated sources attractive for several applications that suffer from speckle noise.     

XYZ particles at Belle

In this paper, I review recent progress in the study of the XYZ particles at Belle. I only focus on studies with charmonium and one or more light mesons in the final states. This covers the X(3872), X(3915),Y(4140), X(4350), and the charged Z states.     

Beyond the LAN: Ethernet’s Evolution into the Public Network

This article details the evolution of Ethernet into Gigabit Ethernet and how this LAN-based technology has undergone major transformations over time. From its data rates and distances to supported media and functionality, Ethernet has greatly improved, enabling it to surmount many of its former limitations and in so doing to expand beyond the LAN into the MAN and now even the WAN. In this article, Pioneer Consulting explores the evolution further by focusing on some of the major technological directions in the Ethernet equipment industry.     

Effect of swift heavy ion irradiation on photoluminescence properties of ZnO/PMMA nanocomposite films

We report a study on the SHI induced modifications on structural and optical properties of ZnO/PMMA nanocomposite films. The ZnO nanoparticles were synthesized by the chemical route using 2-mercaptoethanol as a capping agent. The structure of ZnO nanoparticles was confirmed by XRD, SEM and TEM. These ZnO nanoparticles were dispersed in the PMMA matrix to form ZnO/PMMA nanocomposite films by the solution cast method. These ZnO/PMMA nanocomposite films were then irradiated by swift heavy ion irradiation (Ni⁸⁺ ion beam, 100 MeV) at a fluence of 1×10¹¹ ions/cm². The nanocomposite films were then characterized by XRD, UV-vis absorption spectroscopy and photoluminescence spectroscopy. As revealed from the absorption spectra, absorption edge is not changed by the irradiation but the optical absorption is increased. Enhanced green luminescence at about 527 nm and a less intense blue emission peak around 460 nm were observed after irradiation with respect to the pristine ZnO/PMMA nanocomposite film.     

Optical transmission through an interface between subwavelength slits

This paper studies optical transmission through an interface between two slits with different widths in a sheet composed of an ideal conductor. Such a structure is of potential use in fabricating optical diode and may be the simplest one compared to other designs. Our calculations show that there is a critical wavelength. When the light wavelength is below the critical wavelength, the transmissivity is unidirectional. The expression of the stable transmissivity as a function of the ratio of the widths of the two slits was obtained analytically. Particularly, at the critical wavelength, the transmissivities are zero. This phenomenon has great potential for application in the manufacture of wavelength blockers.     

带有碳杂质的钨中氢稳定性的第一性原理研究

应用第一性原理计算方法研究了碳(C)原子对钨(W)中氢(H)原子稳定性的影响. 本征W中, 当C-H间距离为～2.5 Å时, H的溶解能出现最低值, 此时为H最稳定的位置. W中存在空位时, 由于C的影响, H占据的最佳电子密度面值为0.10 Å^-3. 研究发现, W中单空位最多能容纳10个H原子, 且不能形成H分子, 不同于没有C存在的情况, 表明C对W中H稳定性存在很大影响. 此外, 当两个C原子存在于空位中时, H占据的最佳电子密度面值变为0.13 Å^-3.     

Grain boundary potential and charge density at grain boundaries of chemically prepared thin silver sulfide films

The grain boundary potential and interface state charge density at the grain boundaries of silver sulfide (Ag₂S) thin films prepared by chemical conversion of cadmium sulfide (CdS) films have been determined from the dc resistance of the material and are found to be sensitive to annealing. A reduction in the grain boundary potential and the grain boundary charge density of the film has been noticed when the source CdS film is annealed at different temperatures prior to chemical conversion. The variation in the grain boundary charge density of the grown Ag₂S film with source annealing temperature has been found to be similar to that of thin cadmium sulfide film, reported earlier. An additional low temperature heat treatment of the sample results in an enhancement in the charge density at the grain boundaries. The change in the silver vacancy and/or oxygen and sulfur content of the films as revealed from the energy dispersive spectra of the films suggests possible role of film composition on the grain boundary charge density.     

The Effects of Polarization and Non-Linearity on the Performance of WDM System with Optical Cross-Connects

The performance of a wavelength division multiplexing (WDM) system with optical cross-connects (OXCs) and in the presence of polarization and nonlinear effects was analyzed. We determined the effect of PMD and PDL; nonlinearity such as XPM, SPM, and FWM; and CD on the system performance. We found that the system outage probability is highest at DGD threshold for the respective maximum eye closure (EC). We showed that the allowable DGD depends on the time slot for one bit T, which is the inverse of the network bit rate. Wider T is more immune to large PMD with the EC still maintained at the same level since DGD/T is unchanged. Our analysis also indicated that as DGD increases, BER increases. The BER also increases with increase in PDL and further increases with the presence of XPM, SPM, FWM, and CD.     

Reflections from polished single mode fiber ends

Abstract

The performance of a wavelength division multiplexing (WDM) system with optical cross-connects (OXCs) and in the presence of polarization and nonlinear effects was analyzed. We determined the effect of PMD and PDL; nonlinearity such as XPM, SPM, and FWM; and CD on the system performance. We found that the system outage probability is highest at DGD threshold for the respective maximum eye closure (EC). We showed that the allowable DGD depends on the time slot for one bit T, which is the inverse of the network bit rate. Wider T is more immune to large PMD with the EC still maintained at the same level since DGD/T is unchanged. Our analysis also indicated that as DGD increases, BER increases. The BER also increases with increase in PDL and further increases with the presence of XPM, SPM, FWM, and CD.     

化学发光法测定巯嘌呤的含量

在流动注射系统中,利用巯嘌呤在碱性Luminol-K3Fe(CN)6化学发光体系中发光信号强的特点,建立了一种测定巯嘌呤的新方法。在优化条件下,方法的线性范围是1.02×10-7~1.02×10-9mol.L-1,回归方程是Y=36.315c 140.72(Y是相对发光强度,c是巯嘌呤浓度与10-8mol.L-1的乘积),相关系数是0.998 2,检出限(S/N=3)是6.33×10-10mol.L-1,RSD为3.54%(ci=2.0×10-9mol.L-1,n=12)。该法用于合成样品的测定,简便、灵敏、快速,结果令人满意。文章简要地探讨了巯嘌呤在碱性Luminol-K3Fe(CN)6化学发光体系中的化学发光机理:在反应过程中,产生大量的过氧自由基和羟基自由基,自由基与鲁米诺反应,形成激发态的鲁米诺分子,鲁米诺分子由激发态回到基态产生化学发光现象。