Invited article: an improved double-toroidal spectrometer for gas phase (e,2e) studies

A new spectrometer is described for measuring the momentum distributions of scattered electrons arising from electron-atom and electron-molecule ionization experiments. It incorporates and builds on elements from a number of previous designs, namely, a source of polarized electrons and two high-efficiency electrostatic electron energy analyzers. The analyzers each comprise a seven-element retarding-electrostatic lens system, four toroidal-sector electrodes, and a fast position-and-time-sensitive two-dimensional delay-line detector. Results are presented for the electron-impact-induced ionization of helium and the elastic scattering of electrons from argon and helium which demonstrate that high levels of momentum resolution and data-collection efficiency are achieved. Problematic aspects regarding variations in collection efficiency over the accepted momentum phase space are addressed and a methodology for their correction presented. Principles behind the present design and previous designs for electrostatic analyzers based around electrodes of toroidal-sector geometry are discussed and a framework is provided for optimizing future devices.     

Invited article: The coherent optical laser beam recombination technique (COLBERT) spectrometer: coherent multidimensional spectroscopy made easier

We have developed an efficient spectrometer capable of performing a wide variety of coherent multidimensional measurements at optical wavelengths. The two major components of the largely automated device are a spatial beam shaper which controls the beam geometry and a spatiotemporal pulse shaper which controls the temporal waveform of the femtosecond pulse in each beam. We describe how to construct, calibrate, and operate the device, and we discuss its limitations. We use the exciton states of a semiconductor nanostructure as a working example. A series of complex multidimensional spectra-displayed in amplitude and real parts-reveals increasingly intricate correlations among the excitons.     

Invited article: Vector and Bragg Magneto-optical Kerr effect for the analysis of nanostructured magnetic arrays

Experimental and theoretical aspects of obtaining the magnetic information carried by laser beams diffracted from an array of micro- or nanosized magnetic objects are reviewed. We report on the fundamentals of vector magneto-optic Kerr effect (MOKE), Bragg-MOKE, and second-order effects in the Kerr signal in longitudinal Kerr geometry as well as on an experimental setup used for vector and Bragg-MOKE experiments. The vector and Bragg-MOKE technique in combination with micromagnetic simulation is a reliable tool for measuring the complete magnetization vector and for characterizing the reversal mechanism of lateral magnetic nanostructures. We discuss the Bragg-MOKE effect for three standard domain configurations during the magnetization reversal process and present the expected behavior of the magnetic hysteresis loops.     

靶机接收机空中带飞监测仪的研制

本文结合XX系列靶机空中带飞时对接收机信号监测的实际需要。给出了靶机接收机空中带飞监测仪的功能和技术指标,并在此基础上进行了监测仪的软件和硬件设计。     

Invited article: a [corrected] unified evaluation of iterative projection algorithms for phase retrieval

Iterative projection algorithms are successfully being used as a substitute of lenses to recombine, numerically rather than optically, light scattered by illuminated objects. Images obtained computationally allow aberration-free diffraction-limited imaging and the possibility of using radiation for which no lenses exist. The challenge of this imaging technique is transferred from the lenses to the algorithms. We evaluate these new computational "instruments" developed for the phase-retrieval problem, and discuss acceleration strategies.     

Invited article: A materials investigation of a phase-change micro-valve for greenhouse gas collection and other potential applications

The deleterious consequences of climate change are well documented. Future climate treaties might mandate greenhouse gas (GHG) emissions measurement from signatories in order to verify compliance. The acquisition of atmospheric chemistry would benefit from low cost, small size/weight/power of microsystems. In this paper, we investigated several key materials science aspects of a phase-change microvalve (PCμV) technology with low power/size/weight/cost for ubiquitous GHG sampling. The novel design, based on phase-change material low-melting-point eutectic metal alloys (indium-bismuth, InBi and tin-lead, SnPb), could be actuated at temperatures as low as 72 °C. Valve manufacturing was based on standard thick and thin-film processes and solder technologies that are commonly used in industry, enabling low-cost, high-volume fabrication. Aging studies showed that it was feasible to batch fabricate the PCμVs and store them for future use, especially in the case of SnPb alloys. Hermetic sealing of the valve prototypes was demonstrated through helium leak testing, and Mil spec leak rates less than 1 × 10(-9) atm cm(3)/s were achieved. This confirms that the sample capture and analysis interval can be greatly expanded, easing the logistical burdens of ubiquitous GHG monitoring. Highly conservative and hypothetical CO(2) bias due to valve actuation at altitude in 1 cm(3) microsamplers would be significantly below 1.0 and 2.2 ppmv for heat-treated InBi and SnPb solders, respectively. The CO(2) bias from the PCμV scales well, as a doubling of sampler volume halved the bias. We estimated the shelf life of the SnPb PCμVs to be at least 2.8 years. These efforts will enable the development of low cost, low dead volume, small size/weight microsystems for monitoring GHGs and volatile organic compounds.     

Invited review article: combining scanning probe microscopy with optical spectroscopy for applications in biology and materials science

This is a comprehensive review of the combination of scanning probe microscopy (SPM) with various optical spectroscopies, with a particular focus on Raman spectroscopy. Efforts to combine SPM with optical spectroscopy will be described, and the technical difficulties encountered will be examined. These efforts have so far focused mainly on the development of tip-enhanced Raman spectroscopy, a powerful technique to detect and image chemical signatures with single molecule sensitivity, which will be reviewed. Beyond tip-enhanced Raman spectroscopy and/or topography measurements, combinations of SPM with optical spectroscopy have a great potential in the characterization of structure and quantitative measurements of physical properties, such as mechanical, optical, or electrical properties, in delicate biological samples and nanomaterials. The different approaches to improve the spatial resolution, the chemical sensitivity, and the accuracy of physical properties measurements will be discussed. Applications of such combinations for the characterization of structure, defects, and physical properties in biology and materials science will be reviewed. Due to the versatility of SPM probes for the manipulation and characterization of small and/or delicate samples, this review will mainly focus on the apertureless techniques based on SPM probes.     

电子膨胀阀控制算法验证装置的设计

给出了一种电子膨胀阀及其制冷系统控制算法验证装置的方案,描述了验证装置的原理及其组成.详细介绍了验证装置核心部件控制器的软、硬件设计,验证了几种当前常用的电子膨胀阀及其制冷系统的控制算法.试验结果表明,该装置可以快速、有效地对比出电子膨胀阀及其制冷系统所用控制算法的优劣.     

Invited review article: Photopyroelectric calorimeter for the simultaneous thermal, optical, and structural characterization of samples over phase transitions

The study of thermophysical properties is of great importance in several scientific fields. Among them, the heat capacity, for example, is related to the microscopic structure of condensed matter and plays an important role in monitoring the changes in the energy content of a system. Calorimetric techniques are thus of fundamental importance for characterizing physical systems, particularly in the vicinity of phase transitions where energy fluctuations can play an important role. In this work, the ability of the Photopyroelctric calorimetry to study the versus temperature behaviour of the specific heat and of the other thermal parameters in the vicinity of phase transitions is outlined. The working principle, the theoretical basis, the experimental configurations, and the advantages of this technique, with respect to the more conventional ones, have been described and discussed in detail. The integrations in the calorimetric setup giving the possibility to perform, simultaneously with the calorimetric studies, complementary kind of characterizations of optical, structural, and electrical properties are also described. A review of the results obtained with this technique, in all its possible configurations, for the high temperature resolution studies of the thermal parameters over several kinds of phase transitions occurring in different systems is presented and discussed.     

雷达和雷达干扰实验仪的设计

雷达,雷达对抗课程的教学,需要有一套经济实用并且行之有效的实验设备,本文介绍的由西电电子对抗研究所所研制的雷达/雷达干扰实验仪就可以满足这一要求。本文简单分析了雷达/雷达对抗试验仪的功能和组成。雷达/雷达对抗试验仪是《雷达原理》、《雷达对抗原理》理论教学的重要补充,提供了实践教学的手段。实验仪采用了DDS信号产生技术,数字信号处理(DSP)技术和正交调制技术(QAM),能够完成多个雷达和雷达对抗试验,包含了雷达信号中频、视频处理模块和雷达干扰信号产生模块,同时还具有良好的可扩充性。雷达/雷达对抗实验仪的研制和使用,起到了较好的教学目的,填补了国内高校相关示教仪器的空白。     

Invited review article: The uncertainty in the realization and dissemination of the SI second from a systems point of view

The uncertainty (accuracy) in the realization and dissemination of the SI second is determined by the characteristics of three major components: (1) primary frequency standards, (2) time scale flywheels that provide a continuously present frequency reference, and (3) frequency transfer systems. Currently these three systems contribute at approximately equal levels in the mid 10(-16) range over 20 to 30 days of averaging time to the practical delivery of the SI second to the most demanding users. Any significant improvement in one system requires similar improvements in the other two systems in order for most users to see the full benefits.     

Invited review article: a review of techniques for attaching micro- and nanoparticles to a probe's tip for surface force and near-field optical measurements

Cantilevers with single micro- or nanoparticle probes have been widely used for atomic force microscopy surface force measurements and apertureless scanning near-field optical microscopy applications. In this article, I critically review the particle attachment and modification techniques currently available, to help researchers choose the appropriate techniques for specific applications.     

New plasma measurements with a multichannel millimeter-wave fluctuation diagnostic system in the DIII-D tokamak (invited)

A novel multichannel, tunable Doppler backscattering (DBS)/reflectometry system has recently been developed and applied to a variety of DIII-D plasmas. Either DBS or reflectometry can be easily configured for use in a wide range of plasma conditions using a flexible quasi-optical antenna system. The multiple closely spaced channels, when combined with other fluctuation diagnostic systems, have opened up new measurements of plasma properties. For example, the toroidal and fine-scale radial structure of coherent plasma oscillations, such as geodesic acoustic modes, have been probed simultaneously in the core of high temperature plasmas by applying correlation analysis between two toroidally separated DBS systems, as well as within the multichannel array. When configured as a reflectometer, cross-correlation with electron cyclotron emission radiometry has uncovered detailed information regarding the crossphase relationship between density and temperature fluctuations. The density-temperature crossphase measurement yields insight into the physics of tokamak turbulence at a fundamental level that can be directly compared with predictions from nonlinear gyrokinetic simulations.     

Dynamic model of a continuity flaw during normal magnetization of a ferromagnetic article: II. Magnetostatic field of a continuity flaw during magnetization of the article with a finite-sized magnetizing instrument

A dynamic model of a finite-sized continuity flaw that is present in a ferromagnetic half-space during normal magnetization with a magnetic field produced by a bar magnetizing instrument is obtained. The model takes into account the relative position of the flaw and magnetizing system during the model’s motion along the surface of an article. During normal magnetization of the flaw with the field produced by the finite-sized bar magnet, the longitudinal component of the magnetizing field is shown to exist. The longitudinal component distorts the magnetic-field distribution of the continuity flaw and decreases its detectability.     

多功能空气微生物检测仪监测大气中的细菌含量

采用新型的固体撞击式多功能空气微生物检测仪(JWL—IIB新型)进行大气中细菌的采集和监测,方法简便,结果准确。对于掌握大气中细菌状况,进行城市空气质量评价具有重要的指导意义。     

Possibilities of the magnetodynamic method for testing the thickness of coatings with nonuniform properties (experiment)

In measuring by the magnetodynamic method the thickness of nickel coatings having thicknesses of up to 1000 μ and characterized by an almost maximum spread of structural properties, the possibility of tuning out their effect on the error of measurements was studied experimentally. The testing, to an accuracy acceptable in practice, of nickel coatings in different structural states and components of two-layer (nonmagnetic-ferromagnetic) coatings, i.e., a nickel layer under a chromium layer (regardless of its thickness within a range up to 200 μm), is shown to be ensured by the selection of the primary magnetizing field magnitude of magnetodynamic transducers.     

A new double imaging velocity focusing coincidence experiment: i(2)PEPICO

The vacuum ultraviolet (VUV) beamline of the Swiss Light Source has been upgraded after two years of operation. A new, turntable-type monochromator was constructed at the Paul Scherrer Institut, which allows for fast yaw-alignment as well as quick grating change and exchange. In addition to the original imaging photoelectron photoion coincidence endstation (iPEPICO), a second, complementary double imaging setup (i(2)PEPICO) has been built. Volatile samples can be introduced at room temperature or in a molecular beam, a pyrolysis source allows for radical production, and non-volatile solids can be evaporated in a heated cell. Monochromatic VUV radiation ionizes the sample and both photoelectrons and photoions are velocity map imaged onto two fast position sensitive detectors and detected in delayed coincidence. High intensity synchrotron radiation leads to ionization rates above 10(5) s(-1). New data acquisition and processing approaches are discussed for recording coincidence processes at high rates. The setup is capable of resolving pulsed molecular beam profiles and the synchrotron time structure temporally. The latter is shown by photoelectron autocorrelation, which displays both the 1.04 MHz ring clock frequency as well as resolving the micro-pulses with a separation of 2 ns. Kinetic energy release analysis on the dissociative photoionization of CF(4) indicates a dissociation mechanism change in the Franck-Condon allowed energy range of the first ion state.