超声射流冷却CCl2自由基的激光诱导荧光激发谱

在497—517nm波长范围观测超声射流冷却CCl₂自由基的激光诱导荧光激发谱。得到CCl₂在?←X跃迁中(v₁,v₂,0)←(0,0,0)振动带清晰的K结构。对近80个子谱带作了归属。振动分析给出较精确的v＇₁和v＇₂振动频率和非谐性常数;从K结构的分析得出(A＇-B＇)和(A″-B″)的值,文献未曾报道过。 关键词：     

M/G/1一般减量服务单重休假排队系统的随机分解

本文讨论了M/G/1型一般减量服务单重休假排队模型,运用结构分析法得到稳态队长和服务时间的随机分解的母函数和拉式变换,并给出稳态分布成立的条件及其概率含义．     

Müntz系统{xλn}(λn↘O)有理逼近的Jackson型估计

 设A={λn}∞n=1为一满足λn↘0(n→∞)的实数序列.若λn≤Cn-1/2,n=1,2,…,得到了Lp[0.1]空间Müntz系统{xλn}有理逼近的Jackson型估计:Rn(f,A)Lp≤Cpω(f,n-1/2)Lp,1＜p≤∞.推广了周的相关结论.     

具有分段有界变差系数的三角级数

通过引入所称谓的分段有界变差数列(PBVS),将关于具有非负系数的三角级数的收敛性和可积性的经典结果推广到具有可变系数(允许变号)的三角级数.     

微波消解-塞曼石墨炉原子吸收光谱法检测贝类中的铬

建立了分析贝类样品中铬含量的微波消解-塞曼石墨炉原子吸收光谱法,并对样品前处理方法和检测条件进行探讨.实验结果表明,利用微波消解进行前处理的样品溶样均匀,样品消解完全.石墨炉铬工作曲线浓度范围设定在0.00~15.00μg·L-1之间时,铬浓度与其吸光值呈良好的曲线关系,得出的新合理一元二次方程相关系数r=1.0000.同时对3种贝类样品进行平行测定和加标回收率测定,平行性好,加标回收率保持在82%~95%.并利用国家标准物质海带和贻贝成份分析标准物质进行质量控制,得到的测定值在标准证书的允许误差范围内,相对标准偏差分别为2.93%和2.54%.表明该方法具有操作简便、灵敏度高、准确可靠等优点,适合贝类等水产品中铬含量的检测.     

跨音速自然层流翼型多目标优化设计

应用多目标优化方法在推迟翼型转捩位置的同时,优化激波控制鼓包的位置和外形来减小波阻.经过优化得到多目标问题的Pareto阵面解,通过对其上翼型的气动性能分析发现:优化后翼型的层流区域及激波强度较初始翼型均有改善.结果表明本文方法可以有效地解决层流翼型设计过程中转捩位置和激波强度之间的矛盾.     

环戊酮光电离解离的实验和理论研究

本文介绍了真空紫外光电离质谱结合理论计算研究环戊酮单分子的光电离解离过程. 在9.0∽15.5 eV能量范围内,测量了环戊酮离子及其碎片离子的光电离效率曲线. 通过光电离效率曲线,将环戊酮分子的电离能确定为9.23±0.03 eV,并确认碎片离子为：C₅H₇O⁺,C₄H₅O⁺,C₄H₈⁺,C₃H₃O⁺,C₄H₆⁺,C₂H₄O⁺,C₃H₆⁺,C₃H₅⁺,C₃H₄⁺,C₃H₃⁺,C₂H₅⁺, C₂H₄⁺. 利用量子化学计算方法,在ωB97X-D/6-31+G(d,p)理论水平基础上,提出了C₅H₈O⁺的解离机制. 通过对环戊酮解离路径的分析,发现开环和氢迁移过程为环戊酮离子解离的主要路径.     

Enhancing magnetic dipole emission with magnetic metamaterials

Magnetic dipole(MD) transitions are important for a range of technologies from quantum light sources and displays to lasers and bio-probes. However, the typical MD transitions are much weaker than their electric counterparts and are usually neglected in practical applications. Herein, we experimentally demonstrate that the MD transitions can be significantly enhanced by the well-developed magnetic metamaterials in the visible optical range. The magnetic metamaterials consist of silver nanostrips and a thick silver film, which are separated with an Eu~(3+):polymethyl methacrylate(PMMA) film. By controlling the thickness of the Eu~(3+):PMMA film, the magnetic resonance has been tuned to match the emission wavelength of MDs. Consequently,the intensity of MD emission has been significantly increased by around 30 times at the magnetic resonance wavelength, whereas the intensity of electric dipole emission is well-preserved. The corresponding numerical calculations reveal that the enhancement is directly generated by the magnetic resonance, which strongly increases the magnetic local density of states around the MD emitter and can efficiently radiate the MD emission into the far field. This is the first demonstration, to the best of our knowledge, that MD transitions can be improved by an additional degree of magnetic freedom, and we believe this research shall pave a new route towards bright magnetic emitters and their potential applications.     

Study of the aberrations of the IMP heavy ion microbeam irradiation system

A high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS). A quadrupole focusing system, in combination with a series of slits, has been designed here. The IMP microbeam system is described in detail. The