CP Violation and Flavor Changing Effects in K and B Mesons from Nonuniversal Soft Breaking Terms

We analyze CP violation and flavor changing effects in a minimal supersymmetric standard model with arbitrary nonuniversal soft breaking. Large flavor changing neutral current effects are naturally expected in the K system, even in the absence of quark-squark flavor misalignment. However, the B system is sensitive to new supersymmetric contributions only if nonuniversality implies, not only different soft terms for the three generations but also a large quark-squark misalignment. The only exceptions are processes with a leading chirality changing contribution proportional to tanbeta (as b-->sgamma).     

Closed-form representations for third-order aberrations of two-aspherical mirror aplanats with the mirror tilt and decenter

Approximate equations are derived for imaging aberrations of two-aspherical-mirror aplanats for soft X-ray imaging. These expressions include the Seidel terms for unperturbed states and the axial coma resulting from the tilt and decenter of the mirror surface. A simple analytical method for reducing both the Seidel terms and the axial coma enables us to design novel soft X-ray imaging systems utilizing a wide field of view with reduced sensitivity to mirror misalignments. The method is illustrated by applying it to a two-mirror system for soft X-ray microscopy with a magnification m =−1/50. The design example showed an appreciable reduction in sensitivity, as compared with the existing anastigmatic designs that include a standard Schwarzschild configuration. Imaging aberrations of the novel system are also confirmed by a numerical ray tracing method.     

Beam-induced effects in soft X-ray photoelectron emission microscopy experiments

The beam-induced effects, a consequence of the high photon flux density used in soft X-ray photoelectron emission microscopes in operation at the 3rd generation synchrotron sources, are discussed and illustrated using some representative results obtained with the microscopes at the laboratory Elettra. The focus is on the photon-induced charge potential and chemical degradation, which might be a severe problem for photon-sensible specimens. The possible steps to avoid, reduce or even make use of the beam-induced effects are outlined.     

原子力显微镜用于软X射线接触成像的研究

论述了在接触显微成像技术中，后续放大设备对分辨率的影响，并用实验方法比较了采用光学显微镜和原子力显微镜阅读并放大显微图的结果，表明采用原子力显微镜放大显微图是一种较为理想的方法。     

Gold nanoparticles produced in a microalga

An efficient biological route to production of gold nanoparticles which allows the nanoparticles to be easily recovered remains elusive. Live cells of the green microalga Chlorella vulgaris were incubated with a solution of gold chloride and harvested by centrifugation. Nanoparticles inside intact cells were identified by transmission electron microscopy and confirmed to be metallic gold by synchrotron based X-ray powder diffraction and X-ray absorption spectroscopy. These intracellular gold nanoparticles were 40–60 nm in diameter. At a concentration of 1.4% Au in the alga, a better than 97% recovery of the gold from solution was achieved. A maximum of 4.2% Au in the alga was obtained. Exposure of C. vulgaris to solutions containing dissolved salts of palladium, ruthenium, and rhodium also resulted in the production of the corresponding nanoparticles within the cells. These were surmised to be also metallic, but were produced at a much lower intracellular concentration than achieved with gold. Iridium was apparently toxic to the alga. No nanoparticles were observed using platinum solutions. C. vulgaris provides a possible route to large scale production of gold nanoparticles.     

短波长软X射线多层膜高级次峰设计与制备

考虑了短波长软X射线多层膜的设计问题，比较了一、二、三级布喇格衍射峰设计的反射率结果，分析了反射率与周期厚度及金属层在周期中的比率的关系．本文认为，在存在不连续金属膜层的情况下，用布喇格衍射峰的二级次设计，有助于获得实测的反射率．给出了利用磁控溅射方法沉积的Mo/Si多层膜在4.47nm处同步辐射测量，在60°入射角下获得8.5%实测反射率的结果． 关键词：     

Transmission X-ray microscopy using X-ray magnetic circular dichroism

X-ray magnetic circular dichroism (X-MCD) was used as a large, element-specific and quantitative magnetic contrast mechanism in the soft X-ray microscopes at BESSY I (Berlin) and the ALS (Berkeley). The present state and potential of magnetic transmission X-ray microscopy (MTXM) is outlined. The possibility to record images in varying magnetic fields and the high spatial resolution down to 25 nm were used to image out-of-plane magnetized (4 ?Fe / 4 ?Gd)×75 systems. Magnetic domains could be studied in arrays of circular and square dots with lateral dimensions down to 180 nm. Hysteresis loops of individual dots were deduced using the direct proportionality of the X-MCD contrast to the sample magnetization. Images of a 3 nmCr / 50 nmFe / 6 nmCr film demonstrate for the first time that MTXM is also able to observe in-plane magnetized domains. In the future the possible applications of MTXM will be extended with regard to the strength of the external field, the available energy range and the sample conditions by building a dedicated transmission X-ray microscope for magnetic imaging at BESSY II. Received: 22 May 2001 / Accepted: 4 July 2001 / Published online: 5 October 2001     

软X射线辐射加热金盘靶的X射线再发射

用两台时间关联的软X射线能谱仪观测软X射线辐射((2—6)×10¹²W·cm^-2)加热金盘靶的X射线再发射-从再发射X射线的时间能谱可看出能谱被“软”化-根据加热脉冲时间修正烧蚀热波的稳态自相似解,分析X射线再发射的时间演变过程- 关键词：     

High-resolution X-ray imaging—a powerful nondestructive technique for applications in semiconductor industry

The availability of high-brilliance X-ray sources, high-precision X-ray focusing optics and very efficient CCD area detectors has contributed essentially to the development of transmission X-ray microscopy (TXM) and X-ray computed tomography (XCT) with sub-50 nm resolution. Particularly, the fabrication of high aspect ratio Fresnel zone plates with zone widths approaching 15 nm has contributed to the enormous improvement in spatial resolution during the previous years. Currently, Fresnel zone plates give the ability to reach spatial resolutions of 15 to 20 nm in the soft and of about 30 to 50 nm in the hard X-ray energy range. X-ray microscopes with rotating anode X-ray sources that can be installed in an analytical lab next to a semiconductor fab have been developed recently. These unique TXM/XCT systems provide an important new capability of nondestructive 3D imaging of internal circuit structures without destructive sample preparation such as cross sectioning. These lab systems can be used for failure localization in micro- and nanoelectronic structures and devices, e.g., to visualize voids and residuals in on-chip metal interconnects without physical modification of the chip. Synchrotron radiation experiments have been used to study new processes and materials that have to be introduced into the semiconductor industry. The potential of TXM using synchrotron radiation in the soft X-ray energy range is shown for the nondestructive in situ imaging of void evolution in embedded on-chip copper interconnect structures during electromigration and for the imaging of different types of insulating thin films between the on-chip interconnects (spectromicroscopy).     

Analyses of HF/NH4F buffer-treated Si(111) surfaces using XPS,REM and SIMS

The effect of different cleaning procedures on Si(111) wafers has been studied. A three-step cleaning process was used. The first two steps (thermal oxidation followed by RCA cleaning) were common to all samples. The final step involved rinsing in one of a set of HF/NH4F buffer solutions with a wide range ofpH values. Three different surface techniques were used for characterizing the chemical condition and morphology of the treated surfaces: XPS (X-ray Photoemission Spectroscopy), REM (Reflection Electron Microscopy) and SIMS (Secondary-Ion Mass Spectroscopy). It has been found that thepH value of an HF solution does significantly affect the etching rate and morphology of the Si(111) surface: For the same type of solution, the smaller thepH value, the higher the etching rate. Basic solutions withpH values larger than eight have a much weaker etching effect on the surface, which is contradictory to some previous reports. The most effective solutions for the etching of the Si(111) surface are the solutions of HF buffered by NH₄F, with thepH in the range of 2–6. REM images indicate that the surface morphology after etching in the HF solution is strongly affected by the length of the etching time: Overetching will roughen the surface. The SIMS data show that water rinsing in air during the cleaning process does speed up oxidation, but it is necessary to use water to clean off the residuals from the HF solutions.     

用光线矩阵元描述X射线激光输出特性

采用矩阵光学方法，研究了串接多靶，弯曲靶加反射镜“双程放大”Ｘ射线激光输出特性，给出了发散角普遍公式，分析了电子密度梯度分布，反射镜角失调对Ｘ射线激光输出场分布的影响，所得结果与已有实验符合较好，最后，对如何从靶，Ｘ光学元件空间排布来实现衍射极限的输出发散角提出了新的设想，作了半定量的探讨。     

研究扩散屏障层对Mo/Si多层膜软X射线反射率影响的模拟

在特定波长下,用四层结构模型模拟了Mo/Si多层膜的软X射线反射率.研究了扩散屏障层dMo-on-Si和dSi-on-Mo对Mo/Si多层膜软X射线反射率的影响.研究发现,扩散屏障层并不总是损害Mo/Si多层膜的光学性能,通过合理设计dMo-on-Si和dSi-on-Mo厚度,增加dMo-on-Si与dSi-on-Mo的比值,也能提高多层膜的软X射线反射率.     

A new algorithm for spatial impulse response of rectangular planar transducers

Previous solutions for spatial impulse responses of rectangular planar transducers require either approximations or complex geometrical considerations. This paper describes a new, simplified and exact solution using only trigonometric functions and simple set operations. This solution, which can be numerically implemented with a straightforward algorithm, is an exact implementation of the Rayleigh integral without any far field or paraxial approximation. Additionally, a nonlinear relationship was also established for spatial impulse responses from two field points which share the same projection point on the transducer surface plane. By incorporating this relationship in the algorithm, the computational efficiency of spatial impulse responses and continuous fields is improved about 20-folds and 14-folds, respectively. This algorithm has practical applications in designing l-D linear/phased arrays, 1.5-D arrays and 2-D arrays, as demonstrated through numerical simulations with array transducers. Experiments were also conducted to verify the new solution and results show that the algorithm is both accurate and efficient. The application of this method may include development of ultrasound imaging system for hard and soft tissue nondestructive assessment.     

Statistical investigations of the beam stability of the double-pass amplified zinc soft X-ray laser at 21.2 nm

At the Prague asterix laser system (PALS) of the Academy of Sciences of the Czech Republic the 1-TW asterix iodine laser is used as a pump source for soft X-ray laser experiments. The prepulse technique was applied which is known to enhance the X-ray laser output at the J=0-1 transition dramatically. Since Zn slab targets were used the laser wavelength was 21.2 nm. A prepulse beam having 1.6 J was preceding the main pulse by 10 ns. The main and the prepulse beam are focused by two different optical systems separately. Implementing a half-cavity set-up for double-pass amplification using a Mo/Si multilayer mirror the X-ray laser output was 10 times stronger than at single pass amplification in a 3-cm long plasma. Double-pass amplification was observed to be most efficient when the pump pulse duration was at least 120 ps longer than the round trip time in the half-cavity. Under this fundamental condition the X-ray laser reached saturation in the double-pass regime containing 4 mJ energy what is proved to be enough for applications. In this contribution the X-ray laser features like divergence in two dimensions, the beam quality (symmetry), the pointing angle and the time-integrated output energy are investigated over more than 100 shots. To characterize the stability of the X-ray laser the shot distribution, the mean value and the standard deviation for these parameters are evaluated. For 18 shots in a series -- achieved during one single day -- the corresponding values are given and detailed chi-squared tests characterize the Zn X-ray laser as a robust tool suitable for applications. At PALS soft X-ray laser beam time can be reserved for external research groups.Received: 16 April 2003, Published online: 5 August 2003PACS: 42.55.Vc X- and -ray lasers - 42.60.Da Resonators, cavities, amplifiers, arrays, and rings - 42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation     

软X射线双频光栅干涉诊断等离子体

针对高温稠密激光等离子体临界密度附近电子密度的诊断需求,发展了基于软X射线激光的软X射线双频光栅干涉诊断技术。利用波长13.9nm的类镍银软X射线激光作为探针,掠入射式的双频光栅作为分光干涉元件,对激光辐照金平面靶产生的等离子体进行诊断尝试。实验获得了清晰的干涉条纹图像,充分表明该技术的实用性。但结果中存在靶面不清晰等问题,为此,提出了初步的解决方案。     

New directions in X-ray microscopy

The development of high brightness X-ray sources and high resolution X-ray optics has led to rapid advances in X-ray microscopy. Scanning microscopes and full-field instruments are in operation at synchrotron light sources worldwide, and provide spatial resolution routinely in the 25–50 nm range using zone plate focusing elements. X-ray microscopes can provide elemental maps and/or chemical sensitivity in samples that are too thick for electron microscopy. Lensless techniques, such as diffraction microscopy, holography and ptychography are also being developed. In high resolution imaging of radiation-sensitive material the effects of radiation damage needs to be carefully considered. This article is designed to provide an introduction to the current state and future prospects of X-ray microscopy for the non-expert.     

Study of phase behavior in a system of linear hydrogen-bonded carboxylic acid homologues

The system of hydrogen-bonded liquid crystals formed from binary mixtures p-n-heptyloxybenzoic (I) acid and p-n-undecloxybenzoic (II) acid has been investigated by polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction, and scattering and dielectric measurements. The T–X phase diagram was obtained for this system. All mixtures show enantiotropic smectic and nematic phases. The crystalline phase represents a (α, β) solid solution. At the 2:1 ratio of I to II, an intermediate phase – co-crystal γ – is formed. The co-crystal γ possesses a much wider mesophase range than the corresponding initial components. In contrast to mixtures based on the solid solutions having a positive anisotropy, the co-crystal shows a negative dielectric anisotropy in the mesophase.     

Facility Update: The Center for Advanced Microstructures and Devices: A Status Report

The progress in the field of high resolution X-ray microscopy is caused in particular by the rapid developments of synchrotron radiation sources and X-ray optical elements, by the extension of the energy range, improved designs of X-ray microscopes and scanning X-ray microscopes, the use of CCD detectors with high detective quantum efficiency, the introduction of new imaging techniques, and the development of new fields of application.     

Design of capillary Z-pinch plasma for a soft X-ray laser

An analysis for designing capillary Z-pinch plasma as an alternative active medium of soft X-ray laser is presented. The validity of calculation results are verified by experiment. Namely, the specification of driving current as well as the predicted pinch time is in good agreement with the experimental results. This study also reveals the possibility of reducing the main charging voltage without degrading the performance of the X-ray laser.