高电荷态离子Arq+与不同金属靶作用产生的X射线

研究了高电荷态离子Ar^q+(q=16，17，18)入射金属Be，Al，Ni，Mo，Au靶表面产生的X射线谱.实验结果表明，Ar的Kα-X射线是离子在与固体表面相互作用过程中固体表面之下形成空心原子发射的.电子组态1s²的高电荷态Ar¹⁶⁺离子在金属表面中性化过程中，存在的多电子激发过程使Ar¹⁶⁺的K壳层电子激发产生空穴，级联退激发射Ar的Kα 特征X射线.Ar¹⁷⁺离子在金属表面作用过程中产生的X射线谱形与靶材料没有明显的关联,入射离子的Kα-X射线产额与其最初的电子组态有关，靶原子的X射线产额与入射离子的动能有关. 关键词： 高电荷态离子 空心原子 多电子激发 X射线     

高电荷态离子Arq+与不同金属靶作用产生的X射线

研究了高电荷态离子Arq+(q=16,17,18)入射金属Be,Al,Ni,Mo,Au靶表面产生的X射线谱.实验结果表明,Ar的Kα-X射线是离子在与固体表面相互作用过程中固体表面之下形成空心原子发射的.电子组态1s2的高电荷态Ar16+离子在金属表面中性化过程中,存在的多电子激发过程使Ar16+的K壳层电子激发产生空穴,级联退激发射Ar的Kα特征X射线.Ar17+离子在金属表面作用过程中产生的X射线谱形与靶材料没有明显的关联,入射离子的Kα-X射线产额与其最初的电子组态有关,靶原子的X射线产额与入射离子的动能有关.     

质谱探微

质谱分析法是化学领域中非常重要的一种分析方法，将用于分析的样品分子(或原子)电离成具有不同质量的单电荷或碎片离子，进入由电场和磁场组成的分析器，然后用检测系统进行检测，即可得到不同质荷比的谱线即质谱．通过质谱分析，可以获得分析样品的分子量、分子式、分子中同位素构成和分子结构等多方面的信息．质谱分析法敏感性很强，可以用它追踪各种数量极少的分子．     

高电荷态离子129Xe28+与Au和Mo表面作用产生的X射线谱

研究了高电荷态离子129Xe28+轰击金属Au和Mo表面产生的特征X射线谱.实验结果表明,在入射离子的电荷态和能量相同的条件下,对于核电荷数较小、原子质量较轻的靶原子,只有其内壳层的电子才能被激发而产生X射线,而核电荷数较大、原子质量较重的靶原子只有其较外壳层的电子能被激发而产生X射线.特征X射线的产额随入射离子动能的增加而增加.     

有机电致发光材料8-羟基喹啉铝的结构表征

叙述了制备高纯度有机电致发光材料8－羟基喹啉铝（Alq3)的方法；通过X射线衍射谱、核磁共振谱、红外吸收光谱、质谱、X射线光电子发射谱及荧光光谱测试分析，对Alq3的结构和特性进行了表征。标定了Alq3中喹啉环的存在；分析了Alq3中各个H原子的归属、Alq3分子内部金属离子和配位体之间的相互作用以及该螯合物的分子构型。进一步证实Alq3分子中Al-O键为共价键而非离子键。通过X射线衍射谱分析了样品的化学成分；由X射线光电子发射谱分析了Alq3分子中的电子状态和晶体特性。得到了Alq3的荷质比为459.1以及由于金属Al本身的特性，使得在Alq3中Alq2^ 继续裂解为Alq^ 的几率很小。证实了Alq3的荧光发射光谱位于510nm处（绿光范围），光激发位于喹啉环上而不是金属铝离子。与镓、铟螯合物相比，Alq3中铝离子成键共价性弱，极化力较强。     

氧化物薄膜研制中的电子能谱技术

随着科学技术的不断发展，人们正在寻求更新的实用材料．金属氧化物，包括金属氧化物薄膜的各种实用材料，在工业界、信息产业界和能源开发等方面的应用前景，早已引起国内外学者的极大关注．例如，由于氧化物具有各种特殊的介电和光学性质，研究和开发基于氧化物薄膜的气敏材料非常热门．如何制备出有实用价值的各种薄膜材料，是科学家们一直关心和深入研究的课题．电子能谱技术在各种材料的基础研究和实际应用中起着重要的作用．本文以有序金属氧化物薄膜研制为例，简要评述了电子能谱技术（包括X射线光电子能谱（XPS），紫外光电子能谱（UPS），俄歇电子能谱（AES）和高分辨电子能量损失谱（HREELS）），以及低能电子衍射（LEED）等技术在氧化物薄膜材料制备和表征中的应用．     

单层表面分析方法──低能离子散射和静态二次离子质谱

固体材料的表面特性,例如电子或离子的表面发射或表面吸收,分子的表面吸附,以及表面化学反应等。取决于材料的表面层。特别是最外原子层的组成和结构.自六十年代末期以来,研究表面组成和结构的方法已获得迅速发展[1].这些方法的信息深度范围一般为1—10个原子层,其中低能离子散射和静态二次离子质谱可用于单层表面分析.这两种方法都是用离子束来探测表面的.和用电子束入射的情形类似,用离子束入射时也能引起四种类型的粒子发射:离子散射和二次离子发射;中性粒子溅射;电子发射和光子发射.这些发射原理已构成多种表面的研究方法,见图1.在这些…     

受控核聚变——现代物理学的一个重要前沿领域(之七)

 高温等离子体中原子的特征谱线密集在真空紫外区.所以掠入式光栅光谱仪成为一种重要的诊断工具,一直到软X射线区才逐渐为晶体光谱仪取代、晶体谱仪实质上就是利用晶体中的原子点阵来代替光栅进行光谱分析.在聚变等离子体中随着电子温度的提高,等离子体的轫致辐射和高电离态杂质的线辐射将有相当大的部分是处在软X射线区.这些X射线辐射引起的能量损失是高温等离子体能量损失的重要组成部分,因此从能量损失的观点来看,对X射线的监测是相当重要的.另一方面,X射线的探测和能谱分析可以用来确定等离子体的某些重要物理参数.例如,通过X射线连续谱的测量,可以测定等离子体电子温度;通过X射线杂质谱线多普勒展宽的测量可以测定等离子体离子温度;X射线测量还可以用来诊断等离子体中的杂质成份并用来研究杂质的空间分布及输运过程.因此,X射线的测量在高温等离子体诊断中起着非常重要的作用.     

~(129)Xe~(q+)激发Mo表面产生的X射线谱

研究了高电荷态离子129Xeq+(q=25,26,27)入射金属Mo表面产生的特征X射线谱.实验结果表明,在束流强度小于120nA条件下,高电荷态离子129Xeq+可以激发Mo的L壳层特征X射线谱.单离子X射线相对产额可达10-8量级,特征X射线的相对产额随入射离子的动能和电荷态(势能)的增加而增加.通过Mo原子的Lα1特征X射线谱,利用Heisenberg不确定关系对Mo原子的第M能级寿命进行了估算.     

X射线波长标准

一、引 言 X射线波长是一种物理量,它和其他许多物理常数都有密切的关系,例如用已知波长的X射线精确测定某种晶体的晶面间距,再运用其他已知常数进行计算,可以求出阿伏伽德罗常数 N;利用F=Ne(F为法拉弟常数),可以得出电子电荷e的数值;通过测定e/h,e/me等S数值,可以测出普朗克常数h和电子的静止质量me.高能X射线发射及吸收谱线波长可以提供给核子的β及γ射线谱学作为能量参考标准;利用X射线发射谱线波长以及光电效应,可以直接测定各种元素的原子能级绝对数值,有助于进一步了解元素的化学结构问题.上述各种物理常数虽然也可以通过其他途…     

Secondary Ion Mass Spectrometry Imaging

Secondary ion mass spectrometry (SIMS) is a chemical analysis technique that employs mass spectrometry to analyze solid and low volatility liquid samples [1]. Although there are numerous configurations of SIMS instrumentation, the fundamental basis of SIMS analyses is the measurement of the mass and intensity of secondary ions produced in a vacuum by sputtering the surface of the sample with energetic ion or neutral beams. The sputtering beam is referred to as the primary beam and typically has a kinetic energy of several thousand electronvolts (keV). The primary beam removes atomic or molecular layers at a rate determined principally by the intensity, mass, and energy of the primary species and the chemical and physical characteristics of the sample [2]. Particle sputtering at the kiloelectronvolt level produces a variety of products including electrons, photons, atoms, atomic clusters, intact molecules, and distinctive molecular fragments. A small fraction of these sputter products are ionized, and these ions are the secondary ions in secondary ion mass spectrometry.     

Material Studies in a High Energy Spark Gap

The chemical interactions and physical processes occurring in a high energy spark gap with different combinations of gases, electrodes, and insulators were studied. The electrodes studied were graphite and a tungsten-copper composite; the insulators were Lexan and Blue Nylon; and the gases were N2 and SF6. The gas composition was monitored with a mass spectrometer. Spectroscopic techniques were used to observe the arc channel. The electrode surfaces were studied with several surface analysis techniques, including scanning electron microscopy, electron spectroscopy for chemical analysis, Auger electron spectroscopy, and X-ray fluorescence. The breakdown voltage distribution was examined for different material combinations. The plasma chemistry processes involving the gas, electrode, and insulator materials were found to affect the voltage self-breakdown distribution. The detailed surface analysis gave information about the nature of the chemical processes. The presence of Blue Nylon seemed to have a more adverse effect than Lexan and graphite seemed to have a narrower voltage distribution than the tungsten-copper composite.     

Surface investigation of solids by the statical method of secondary ion mass spectroscopy (SIMS)

The physical and chemical properties of a solid surface are determined by its uppermost monolayers. Besides other methods like Auger electron spectroscopy (AES) and X-ray electron spectroscopy (ESCA) for example, the chemical composition of these uppermost monolayers can be investigated by the statical method of secondary ion mass spectroscopy (SIMS). In this method a relatively large target area (0.1 cm²) is bombarded with a small primary ion current density (10^?9 A cm^?2). Thus a sputtering time of several hours is achieved for an individual monolayer. A mass analysis of the emitted positive and negative secondary ions gives information about the chemical composition of the uppermost monomolecular layer of the bombarded surface. Important features of SIMS are: detection of chemical compounds; isotope sensitivity; detection of hydrogen and its compounds ; depth resolution in the range of a single monolayer ; low detection limits (< 10^?6 monolayer or < 10^?14 g) for many elements and compounds.The capacity of this method is demonstrated using as examples the initial surface oxidation of metals and semiconductors and adsorption phenomena on clean metal surfaces. In some special cases additional information on the chemical composition of the uppermost monolayer can be obtained by the electron induced ion emission from the surface.     

Impurity composition and cleaning of the cylindrical surface of CVD single-crystal tungsten

Secondary-ion mass spectrometry (SIMS), Auger electron spectroscopy (AES), and low-energy electron diffraction (LEED) methods are used to determine the chemical composition on the surface and in the near-surface layer of CVD cylindrical single-crystal tungsten, which is applied as the emitter material in thermionic thermal-to-electrical energy converters in space-borne nuclear power plants. Results obtained are compared with those for reference perfect plane-parallel W(110).     

Crossed beam measurement of binding energies of positronium compounds: A proposal

We describe an experiment to establish the chemical stability and measure the binding energies of compounds containing positronium atoms. The method consists of crossing a monoenergetic beam of low energy (1–25 eV) positrons with a supersonic adiabatic expansion molecular beam, and, after a dissociative attachment reaction takes place, detecting the resulting ¡gnature ion while measuring its kinetic energy. Except for the use of a positron beam instead of an electron beam, this is similar to electron impact MS/IKES (mass spectrometry/ion kinetic energy spectrometry). The start signal for the IKES measurement is provided by the remoderation of the positron beam. Among the benefits of the proposed research are the study of: (1) a new class of resonances, those involving temporarily bound positrons to molecules in excited electronic states; and (2) the surprising sub-threshold fragmentation observed by Surko and Hulett in positron-molecule scattering.     

Challenge towards muonic atom formation with unstable nuclei

X-ray spectroscopy of muonic atoms is an important tool to obtain information on the nuclear charge distribution of nuclei. It has been successfully used for many years to study stable isotopes in condensed or gaseous states. A new method has been proposed to extend muonic atom X-ray spectroscopy to the use of radioactive isotope beams to form muonic atoms with unstable nuclei. This new method allows studies of the nuclear properties and nuclear sizes of unstable atoms by means of the muonic X-ray method at facilities where both negative muon and radioactive nuclear beams would be available. Progress of a feasibility study at RIKEN-RAL muon facility is also reported. Received: 1 May 2001 / Accepted: 4 December 2001     

On Auger electron spectroscopic measurements of ZnCl2 —coal interaction

By combining electron stimulated desorption (ESD) with low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and work function change (Δφ) measurements the information content of ESD with regard to surface structure and composition is examined, using the surface systems O/W(100) and O/W(110). Although it is not possible to separate the local interaction from the ion escape phase, the comparison of the ESD results with Information derived from LEED, AES and Δφ and the use of simple models of the local interaction gives a rather detailed picture of the location and environment of adsorbed atoms which provides a reasonably reliable basis for the interpretation of UPS spectra of adsorption layers.ESD is extremely sensitive to adsorbed layers. The fact that the ion signal depends not only on coverage but also on the structure and structure-dependent properties of the adsorbate makes on the one hand coverage determination difficult if not impossible, on the other hand opens the door to structure analysis. The potential for obtaining structure information can be easily assessed by comparison with electron probe results.In comparison with other ion probes such as ion scattering spectroscopy and secondary ion mass spectroscopy, ESD is at present the most promising ion probe method for obtaining information on the location of adsorbed atoms from angular and energy distribution measurement (ESDIAD and ESDIED). This is clearly seen by the comparison with the structural data derived from LEED, AES and Δφ measurements for the complex system O/W(100). The consistency of the data obtained with ESD and electron probe techniques lends strong support to the simple models on which the analysis of the ESD results from chemisorbed layers are based. The comparison of ESD results from the system O/W(100) at high coverage and from O/W(110) with 0⁺ ion emission from oxides shows, however, that caution is in place when assigning ESD features to atoms chemisorbed on the metal surface. Without a careful analysis of the ion energy, threshold and/or cross-section such ions cannot be distinguished from ions produced by dissociation of oxides which may be present on the surface only in small quantity. These ions usually are not related to the chemisorbed species which covers most of the surface and therefore dominates the signals seen with (nearly) all other surface probes.If the consistency of LEED, AES, Δφ and ESD data for O/W(100) is not fortuitous, then ESD has already given some important feed-back to the electron probe techniques: the structural models derived from vibrational ELS spectra have to be revised. Increasing accumulation of experimental data and deepening of the theoretical understanding of the physical processes involved in ion emission will have to show how much further information complementary to that from electron probes can be obtained from ion probes.     

X射线光电子能谱

X射线光电子能谱（X-ray photoelectron spectroscopy，XPS）技术也被称作用于化学分析的电子能谱（electron spectroscopy for chemical analysis，ESCA）．XPS属表面分析法，它可以给出固体样品表面所含的元素种类、化学组成以及有关的电子结构重要信息，在各种固体材料的基础研究和实际应用中起着重要的作用．文章简要介绍了XPS仪器的工作原理和分析方法，并给出了XPS在科学研究工作中的应用实例．     

多金属氧酸盐TBA3[VW5O19]及TBA4[PVW11O40]的固体核磁共振研究

多金属氧酸盐（简称多酸,Polyoxometalates,POMs)是由处于d⁰电子构型的前过渡金属元素通过共边或共角缩聚而成的金属-氧簇类化合物．由于其具有丰富的分子结构和独特的物理化学性质,已经被广泛应用于功能材料、催化化学和药物化学等领域．其中钒取代的多酸阴离子具有很好的催化活性,特别是对烃类的氧化,它的活性主要受钒取代的数目和钒中心的阴离子环境这两个因素影响．该文利用固体核磁技术分析了一取代钒的两类典型结构中⁵¹V的局域结构和化学环境,以及有机阳离子对多酸阴离子结构的影响,特别是对⁵¹V的化学环境的影响,为研究多酸的催化活性和催化机理提供基本的结构信息．