Detection limits in XPS for more than 6000 binary systems using Al and Mg Kα X‐rays

A simple approach to estimating the detection limits of X‐ray photoelectron spectroscopy (XPS) for any element in any elemental matrix is presented, using the intensity of the background at the expected position for the photoelectron peak to be detected. The approach has been extended to estimate the detection limit for all elements from lithium to bismuth in a similar range of elemental matrices. Using a number of assumptions, it is possible to obtain a reasonable estimate of the background intensity at any electron kinetic energy in the XPS spectrum of an element. Therefore, a detection limit for an arbitrary element homogeneously distributed in that matrix can be estimated. The results show that, although most elements are detectable at about the 1 at.% to 0.1 at.% level, for heavy elements in a light element matrix, the detection limit can be better than 0.01 at.%, whereas for light elements in a heavy element matrix, detection limits above 10 at.% are not uncommon. Two charts detailing the detection limits for all combinations of trace and matrix elements from lithium (Z = 3) to bismuth (Z = 83) are provided for Al Kα and Mg Kα X‐ray sources using a typical hemispherical analyser instrument which provides 10⁶ counts eV for the Ag 3d_5/2 peak from pure silver. These detection limits can be scaled to estimate the detection limits for any given instrument and operating conditions if the intensity of the Ag 3d_5/2 peak from pure silver under those conditions is known. © 2014 Crown Copyright. Surface and Interface Analysis © 2014 John Wiley & Sons Ltd.     

Excitation of microwave by an annular electron beam in a plasma-filled dielectric lined waveguide

An axial relativistic electron beam passing through a slow wave structure is unstable to an electromagnetic perturbation whose phase velocity equals the velocity of the beam. This phenomenon of Cherenkov emission is the basis of all traveling wave tubes. In this paper an excitation of Cherenkov radiation by a thin annular relativistic electron beam in a plasma-filled dielectric-lined waveguide is analysed by use of the self-consistent linear theory. The effect of the thin annular electron beam on the beam-wave interaction is completely described by a jump condition. The dispersion equation and the simultaneous condition of the beam-wave interaction are derived. Finally, the growth rate of the wave is obtained, and the effect of the background plasma density and the electron beam radius on the growth rate of the wave are presented.This work is supported by National Natural Science Foundation of China.     

The Shirley background revised

Some aspects of the theory and the practical application of the Shirley background correction procedure are reviewed. The ‘classic’ Shirley/Sherwood method is scrutinized, with special emphasis on the physical meaning and the correct implementation. The features of the classic and the cross-section-based Shirley background correction procedures are compared. With a simple modification to the recently discovered Shirley-equivalent inelastic energy loss cross-section a ‘physical’ cross-section is derived and its impact on the practical data evaluation is analyzed. The impact of some frequently used erroneous implementations on the physical meaning of the evaluation procedure as well as the practical results derived using the wrong implementation are discussed and the correct statement on the physical meaning and implementation method is also suggested.     

第一讲微波背景辐射的各向异性、偏振及宇宙电离的历史

文章对微波背景辐射的各向异性、偏振及宇宙电离的历史给出了评述性介绍．从大爆炸理论的预言，到观测的发现，到其各向异性及偏振的探测，微波背景辐射(CMB)向人们揭示了丰富的宇宙学信息．文章在对基本理论作了简单介绍后，着重讲述了最新的CMB的观测结果及其物理意义．特别对微波背景各向异性探测器(Wilkinson Microwave Anisotropy Probe，WMAP)的偏振观测及其对宇宙重新电离的限制给出了较详细的叙述．     

天候、背景对微光观察仪探测距离的影响

微光观察仪是在微弱光条件下用来观察目标的一种仪器,探测距离是它的一项重要指标。介绍了用实验方法研究天候、背景对微光观察仪探测距离的影响。根据照度的不同,通过测量出夜视仪的作用距离,可准确地表示出人在夜间对目标发现、识别、辩认的程度。将一个目标同其所处的背景或其它目标相区别,得出了具有一定价值的结论。     

BEPCⅡ束流相关本底的蒙特卡罗模拟研究(Ⅲ)——Touschek效应

介绍了Touschek效应本底研究的意义、Touschek效应的作用原理和建模方法. 使用自主开发及通用的模拟工具, 系统研究了BEPCⅡ工作条件下BESⅢ主要探测器的Touschek本底. 模拟和计算束流寿命的比较表明当前的模拟结果是有参考价值的, 建模方法是可行的. 探测器的模拟结果表明Touschek本底不会影响将来BESⅢ的正常稳定运行, 不会造成探测器的辐照损伤.     

谈线性代数与空间解析几何的整合

线性代数与空间解析几何的产生、发展,意味着它们是不可分割的两部分,本文分析和论述了线性代数与空间解析几何整合的必要性和可行性.     

Are the Peaks in the Cosmic Microwave Background Really Acoustic?

It is shown that the widely accepted interpretation of the peaks in the CMB as acoustic oscillations seems to be not correct. It is further shown that the peaks correspond to the extension of galaxies in a non-standard scenario of galaxy formation forwarded by the author in a previous paper. Hence this result and the generating mechanism of the peaks by amplification of zero-point quantum oscillations in the very early universe as proposed by Bose and Grishchuk might complement one another to an overall picture of galaxy formation.     

New development in in-capillary electrophoresis techniques for kinetic and inhibition study of enzymes

Enzymes are often quantified by measuring their biological activity. Capillary electrophoresis is gaining its position in this field due to the ongoing trend to miniaturize biochemical assays.     

基于非参数特征提取的早期林火烟雾检测

提出了一种基于非参数特征提取的早期森林火灾烟雾检测方法。采用双背景模型进行运动区域检测,得到可疑烟雾区域。再利用早期火灾烟雾颜色特征和运动特性对提取的可疑运动区域进行颜色判别,对增长区域以及上升区域进行检测,排除部分干扰目标。根据提出的非参数特征提取法,计算并科学地选取可疑区域的特征量,将其输入训练好的支持向量机(SVM)进行烟雾判别。对多段视频进行测试表明,该方法能适用于复杂多变的野外环境,排除干扰,有效地检测出早期林火烟雾。