Evaluation of a magnetically coupled microcavity hollow cathode discharge for atomic emission spectroscopy

A magnetically coupled microcavity hollow cathode discharge device was evaluated for its analytical potential as a boosted atomic emission source. A magnetic field using an electromagnet was applied perpendicular to the axis of the microcavity hollow cathode. The intensity of the atomic emission of copper, aluminum and the ionic emission of magnesium increased with increasing magnetic field until it reached a maximum. A further increase in the field strength did not lead to an enhancement of these emissions. The attainment of the maxima was attributed to the increase in the electron temperature and radial diffusion of the electrons from the center of the microcavity axis. Electron temperatures in the presence of the magnetic field calculated based on the semicorona model were shown to be proportional to the square of the reduced field strength. Further, these maxima were correlated to the energies of the upper levels of the transition studied.     

从核磁共振氢谱推导的重质油氢碳原子摩尔比计算式

通过对炼油厂的催化油浆、重催油浆和催化重焦蜡油核磁共振氢谱中质子归属和重质油结构的假设，推导出计算这3种重质油的氢碳原子摩尔比计算式；结果表明，氢碳原子摩尔比的计算值与实测值非常接近，平均误差仅为3．1％。     

2,4,6-三硝基-2,4,6-三氮杂环己酮生成历程的~(15)N NMR研究

由DPT与脲或硝基脲在硝化剂中反应可以合成2,4,6-三硝基-2,4,6-三氮杂环己酮。本文用~(15)N示踪原子对DPT分子中不同位置的氮原子分别进行标记,用~(15)N NMR谱图来考察~(15)N标记的反应物和产物分子中标记原子的位置及丰度。结果表明,与脲或硝基脲缩合的DPT硝解碎片为非硝基取代的N,N-二羟甲基胺,硝基脲上硝基与硝化剂之间存在着交换反应。     

氯磺化聚乙烯结构和性能研究Ⅰ.氯磺化反应及其对晶体结构的影响

氯磺化聚乙烯水解后是一种性能特异的离子交换膜。本文研究了低密度及高密度聚乙烯中空纤维氯磺化反应时间与交换容量之间的关系,并用红外光谱及广角X射线衍射法测定了氯磺化反应对聚乙烯晶体结构的影响。结果表明,氯磺化反应主要发生在聚乙烯的非晶区,最大交换容量及反应速度均与非晶区含量有关。反应对晶粒表面也有一定程度的侵蚀作用,随着交换容量的增加,结晶度下降,晶粒度减小。低密度及高密度聚乙烯的变化趋势相似,但前者比后者变化更显著。     

O(~1D)+Si(CH_3)_3Cl反应生成振动激发的OH(υ≤5)

实验光谱学和理论计算都发现,“重原子”能隔离分子中的某些振动能景,如SiH_4中Si—H振动泛频的“局域模”.Roger 等在研究F 原子与M(CH_2CH=CH_2)_4(M=Sn,Ge)的反应中,发现了Sn,Ge 对过剩能量转移到其它部分有强烈的阻碍作用(在中间态的寿命时间内).最近,在研究O(~1D)+M(CH_3)_4生成OH(v)反应中,观测到类似的现象.M=C 时,Lutz 用激光诱导荧光方法检测OH 的振动分布,振动是冷的,v=1与v=0的布居比为0.05,     

Kinetic study of the reaction of CH3O with Br and Br2

The title reactions have been studied at room temperature by applying the discharge flow method coupled with laser induced fluorescence detection of methoxy radicals and resonance fluorescence detection of bromine atoms. The following rate constants were determined: CH₃O + Br Õ products (1) k ₁ (298 K) = (3.4 ± 0.4 (1)) × 10¹³ cm³ mol^-1 s^-1, CH₃O + Br₂ Õ products (2) k ₂ (298 K) £ 5 × 10⁸ cm³ mol^-1 s^-1.     

Atom-probe field ion microscopy

The atom probe field ion microscope (AP-FIM) is a combination of a field ion microscope and a time-of-flight mass spectrometer with a single ion detection sensivity. With the field ion microscope topology of a surface, surface reactions and surface modifications can be studied in atomic detail. By time-of-flight measurements surface layers and interface layers can be chemically analyzed atom by atom and atomic layer by atomic layer. Compositional variations according to surface or interface segregation, precipitations, or surface changes in corrosion or in electrochemical layer formation etc. can be studied quantitatively on a subnanometer scale. Some of our studies on related problems will be decribed briefly.     

超球谐展开的收敛行为He原子的^3S态

利用相关函数－超球谐－广义Ｌａｇｕｅｒｒｅ函数方法，研究Ｈｅ原子＾３Ｓ态波函数向超球谐函数展开的收敛行为。截止于ｌ＝０，１，２的超球谐函数给出的本征能分别与组态相互作用的ｓ－，ｓｐ－，ｓｐｄ－极限能一致。仅用４４个超球谐函数，便得到了与精确的ＨｙｌｌｅｒａａｓＣＩ变分能量小数点后第５位的２＾３Ｓ，３＾３Ｓ的４＾３Ｓ态本征能吻合。     

金属Cu低指数表面熔化行为的分子动力学模

采用Mishin镶嵌原子势, 通过分子动力学方法模拟了金属Cu的低指数表面在不同温度的表面熔化行为, 分析了熔化过程中系统结构组态的变化以及固-液界面迁移情况. 金属Cu的(100)和(110)表面在低于熔点发生预熔化, 而(111)表面存在明显的过热现象. 准液体层的厚度随温度升高而增加, 热稳定性与表面的密排顺序一致, 按(111)、(100)、(110)顺序增大. 当温度高于热力学熔点时, 固液界面的移动速度与温度成正比, 外推得到热力学熔点约为1360～1380 K, 与实验结果1358 K吻合良好. 动力学系数定义为界面移动速度与过热程度的比值, 表现为明显的各向异性: k100=39 cm•s−1•K−1, k110=29 cm•s−1•K−1, k111=20 cm•s−1•K−1. k100与k110之间的比例符合collision-limited理论, (111)密排面有与其它低指数表面不同的熔化方式.