Measurement and calculation of electrostatically induced voltage generated on an ungrounded metal box

When a charged body passes by the front of an ungrounded metal box such as a box of electronic equipment, an electrostatically induced voltage is generated. The induced voltage can cause malfunctions and failure of the equipment. However, whether a voltage is induced in the metal box by a moving charged body and how much is induced is not clear. In this study, measured induced voltages are compared with values calculated for two capacitance-measuring methods. The results will be helpful to estimate the possibility of malfunction and failure by induced voltage and whether a standard test method should be considered.     

Electrostatically induced potential difference between conductive objects contained in a partially opened metal box

When a charged body exists near an opening of a partially opened metal box of an electronic apparatus, a potential difference is induced between conductive objects contained in the box. If the charged body moves, the potential difference changes and is capable of causing the breakdown of microelectronic devices in the box. However, one can rarely find a thorough study of this voltage. In this study, a potential difference induced between two metal foils in the partially opened metal box is measured without electrical connections. In some experiments, a piece of foil is grounded, whereas in others, both foils are ungrounded (floating). The measured result shows that the potential difference for a piece of foil grounded in the box is approximately 80% larger than that for both foils ungrounded. The potential difference decreases linearly by increasing the logarithm of the distance between the charged body and the front of the metal box. The result will provide a basis for a design to prevent the possible malfunction and breakdown of electronic apparatuses.     

Statistics of count numbers from a photomultiplier tube and its implications for error estimation

We present investigations of counting statistics for five different luminescence-measuring systems. The dark current background and the counts obtained for a PM tube under constant illumination at various light intensities were measured. Where no divider is present in the counting system, the standard deviation of the number of counts exceeds the value predicted by a Poisson distribution but by different amounts in the different systems. This has implications for analysis of the uncertainties in the estimated equivalent doses and other quantitative analyses of luminescence measurements. We suggest how to account for the observed overdispersion of count numbers in uncertainty estimation.     

Measuring stresses in thin metal films by means of Raman microscopy using silicon as a strain gage material

Mechanical stresses in microelectronics and micro‐electromechanical systems may influence the reliability of applications and devices. The origin of the stresses can be because of the joining of dissimilar materials with regard to the thermal expansion coefficient, electromigration or the deposition process utilized. Stresses can lead to delamination, crack formation and stress migration and therefore to a failure of the device. Identifying the locations of highest stresses in a device is crucial for reliability improvement. Currently, both Laue X‐ray micro diffraction and convergent‐beam electron diffraction are able to locally determine the stresses in thin metal films. Here, we propose a modified method of indirect Raman microspectroscopy to measure stresses with a lateral resolution in the submicrometer range at a laboratory scale. The method encompasses the crystallization of an amorphous silicon layer by local laser annealing and its subsequent usage as a strain gage. Stresses in an aluminum thin film were determined as a function of temperature. In addition to the average stress, the stress distribution could be monitored. Copyright © 2009 John Wiley & Sons, Ltd.     

Measuring magnetic fields in plasmas by means of light scattering

The theory of light scattering in plasmas containing a magnetic field yields the special case of modulated scattering spectra. The modulation frequency is governed by the field in the plasma and is equal to the electron cyclotron frequency. In this investigation magnetic fields in a plasma were determined by a laser scattering experiment. The experimental data were: electron densityn _e=10¹⁶cm^?3, electron temperatureT _e=3.2 eV, scattering angle θ=90 °, scattering parameter α=0.6, and a maximum field in the plasma of 125 kG. The spectrum measured at the maximum magnetic field was modulated with 3.6 × 10¹¹ Hz. In scattering experiments with a field reduced by about 20% the observed modulation frequency was 2.8 × 10¹¹ Hz. A thermal spectrum with a smooth profile was found when no field was present in the plasma. Applying the theory of cyclotron modulated spectra one obtains from the scattering experiment magnetic fields of 128, 100, and 0 kG. Within the experimental accuracy these values agree well with the fields determined by means of magnetic probes. Other possible interpretations of the measured deviations from thermal spectra (modulation with the plasma frequency or additional cold electron components in the plasma) are discussed, but they afford no explanation. This experiment has domonstrated that magnetic fields in plasmas can be measured locally and almost without disturbance by means of light scattering.     

Multiple ionization of neon 2s- and 2p-electrons induced by ion atom collisions

Absolute cross sections for production of the 1s ²2s2p ⁵ and 1s ²2s ⁰2p ⁶ configurations of neon in collisions of H⁺, He⁺, and Ne⁺ with Ne and He have been measured by observation of radiative transitions in the spectral range of the vacuum ultraviolet for energies between 50 keV and 1 MeV. Projectile and target emission have been separated. The dependence of the cross sections upon impact velocity is discussed and compared with theoretical calculations. The relative population of the¹ P ₁ and³ P _{2, 1, 0} and the³ P _{2, 1, 0} fine structure levels of the 1s ²2s2p ⁵ configuration is measured as function of impact velocity for the different projectile target combinations.     

Spin and valley half metal induced by staggered potential and magnetization in siliceneSpin and valley half metal induced by staggered potential and magnetization in siliceneSpin and valley half metal induced by staggered potential and magnetization in silicene

We investigate the electron transport in silicene with both staggered electric potential and magnetization; the latter comes from the magnetic proximity effect by depositing silicene on a magnetic insulator. It is shown that the silicene could be a spin and valley half metal under appropriate parameters when the spin-orbit interaction is considered; further, the filtered spin and valley could be controlled by modulating the staggered potential or magnetization. It is also found that in the spin-valve structure of silicene, not only can the antiparallel magnetization configuration significantly reduce the valve-structure conductance, but the reversing staggered electric potential can cause a high-performance magnetoresistance due to the spin and valley blocking effects. Our findings show that the silicene might be an ideal basis for the spin and valley filter analyzer devices.     

Resistance switching driven by polarity and voltage of electric pulse in AgLa0.7Ca0.3MnO3Pt sandwiches

Materials showing reversible resistance switching at room temperature are attractive for todays semiconductor technology with its wide interest in nonvolatile random access memories. In this letter, the switching between the high resistance state (OFF-state) and the low resistance state (ON-state) was demonstrated, which depends on both polarity and magnitude of the applied electric pulse. Such a phenomenon could be useful for various magnetic and electric device applications. A conductance channel model is proposed to explain the observed effect. This mechanism is supported by the experimental data obtained from the multi-resistance states measured synchronously. PACS  72.80.-r; 73.40.-C; 75.70.-i     

Structural characterization of pumice-supported silver-palladium metal clusters by means of XAFS and AWAXS

Silver-palladium bimetallic clusters were synthesized on pumice by the reduction of aqueous solution of metal salts with different Pd:Ag ratios. Used as bimetallic catalysts, in hydrogenation reactions, in situations where molecules can undergo several different reactions, they eliminate undesired reactions and maximize the desired ones. To characterize the structure of these bimetallic catalysts and control if the two metallic elements do mix or not to each other to form an alloy, the structure of the Ag-Pd bimetallic clusters was investigated by means of X-ray-absorption fine-structure spectroscopy (XAFS) and anomalous wide angle X-ray scattering (AWAXS) experiments performed at the European Synchrotron Radiation Facility (ESRF) using the GILDA and the BM16 beamlines. A correlation between Ag and Pd was found but not a clear evidence of alloying. Received: 21 December 1998 / Received in final form: 19 March 1999     

Investigation of electron transfer processes in organic molecules and metal complexes by means of electrolysis-EPR

Kinetics of electrochemical reduction of trialkylphosphates, slow homogeneous electron transfer reaction with the participation of paramagnetic intermediates and multispin Co(II)-, Cu(II)-, Zn(II),-nitroxyde radical systems reduction processes are studied with the help of combining electrochemical method and EPR.     

激光透射成像法测量石英管的外径与壁厚

为了同时同位测量石英管的外径和壁厚,建立了激光透射成像系统,对系统测量原理进行研究。基于几何光学和菲涅尔公式,分别导出平行光垂直照射石英管后的透射光线偏向角、相对光强与入射光线离轴距离之间的关系;通过数值计算,分析了偏向角、相对透射光强随入射光线离轴距离的变化特点;针对物方远心光路,分析了光阑对偏向角和相对光强的限制;基于CCD成像原理,通过引入标定系数和补偿因子,导出石英管外径与壁厚的计算公式。实验结果表明:外径绝对误差和相对误差的平均值分别为0.119mm和0.91%,壁厚绝对误差和相对误差的平均值分别为0.153mm和6%。     

Effect of metal surface morphology on nano-structured patterns induced by a femtosecond laser pulse and its experimental verification

The effect of material surface morphology on the periodic subwavelength of nano-structures induced by a femtosecond(fs) laser was investigated systematically from the initial surface roughness, the different scratches, the pre-formed ripples, and the layer-carving technology experiments. The results of the comparative experiments indicate that the initial surface conditions of the target surface have no obvious effects on the spatial structured periods(SSPs) and the ripple orientation of the periodic nano-structures induced by a fs laser, which agreed well with the foretold present surface two-plasmon resonance(STPR) model. Furthermore, different shapes of nanogrids with high regularity and uniformity were obtained by fs-laser fabrication.     

Attenuation of flexural vibration for floating floor and floating box induced by ground vibration

This paper investigates the vibration isolation performance of floating floor and floating box structures to control rail vibration transmission. Simple theoretical and experimental methods are developed to analyze the effects of stiffener beam, mass and arrangement of isolator on the fundamental natural frequency of the flexural vibration of floating floor and box structure.The vibration reduction performances of floating floor and box structure are found to be degraded by flexural vibration of the floor or supporting stiffener beam. From the results of vibration measurements; stiffener beams increase the fundamental natural frequency of flexural vibration of floating floor and enhance vibration isolation. Also they can further alleviate the effect of flexural vibration using optimum isolator arrangement effectively. The proposed floating box design achieved a vibration reduction of 15-30 dB in frequency region of critical rail vibration (30-200 Hz).     

On the production of photon-anticorrelation effects in a degenerate parametric amplifier by means of partially coherent light fields

In order to obtain anticorrelated photons by means of nonlinear optical interactions, e.g., in an optical parametric amplifier, the incident light fields have to fulfill stringent criteria, which are calculated in the present paper. It is found that light fields with anticorrelated photons can only be obtained if the relative intensity fluctuations of the pump field are smaller than 2.5×10^–3.     

Spin and valley half metal induced by staggered potential and magnetization in silicene

We investigate the electron transport in silicene with both staggered electric potential and magnetization; the latter comes from the magnetic proximity effect by depositing silicene on a magnetic insulator. It is shown that the silicene could be a spin and valley half metal under appropriate parameters when the spin–orbit interaction is considered; further, the filtered spin and valley could be controlled by modulating the staggered potential or magnetization. It is also found that in the spin-valve structure of silicene, not only can the antiparallel magnetization configuration significantly reduce the valve-structure conductance, but the reversing staggered electric potential can cause a high-performance magnetoresistance due to the spin and valley blocking effects. Our findings show that the silicene might be an ideal basis for the spin and valley filter analyzer devices.     

Membrane tube pearling induced by a coupling of osmotic pressure and nanoparticle adhesion

ABSTRACT

In this work, a coarse-grained molecular dynamics simulation method that belongs to the class of dissipative particle dynamics scheme with implicit solvent was used to indicate that adsorption of nanoparticles (NPs) inside a lipid membrane tube and pressure difference across the membrane, e.g. osmotic pressure, cooperatively induce membrane tube pearling. We demonstrate that NP adsorption and aggregation initiate the shape transformation of the lipid tube, and pressure difference provides a driving force for pearling transition. Depending on the dynamic coupling of tube shape transition and NP aggregation in the interior of the tube, different shape transitions via four kinds of pearling pathways are recognised, including pearls on a string (i.e. vesicles are interconnected via either a chain or double-chain of NPs) and tube-to-vesicle transition that is dominated kinetically either by NP-membrane attraction or by pressure difference. Considering the fact that biological membranes are semipermeable and many proteins interact with the membranes, these findings not only provide a mechanism of membrane tube pearling but also demonstrate the importance of osmotic pressure and protein–membrane interaction for many cell activities related to shape transitions of biomembrane.     

Visible fluorescence induced by the metal semiconductor transition in composites of carbon nanotubes with noble metal nanoparticles

We show that single-walled carbon nanotube (SWNT) bundles emit visible fluorescence in the presence of noble metal nanoparticles and nanorods in the solid state. Conductivity measurements with metallic nanotubes, isolated from pristine SWNTs, show that they become semiconducting in the presence of the metal nanoparticles. Nanoparticle binding increases the defects in the nanotube structures which is evident in the Raman spectra. The metal-semiconductor transition removes the nonradiative decay channels of the excited states enabling visible fluorescence. Nanotube structures are imaged using this emission with resolution below the classical limits.     

Excitation of optically forbidden transitions in argon and neon by electron impact

A radial electron monochromator and analyser system employing several new features has been used to study low energy differential inelastic electron scattering by ground state argon and neon atoms. Angular distributions for a number of optically inaccessible states are reported at energies between 30 and 100 eV and over a range of scattering angles from 0–90°. In particular, results are shown for the metastable states (³P₂, ³P₀) of argon as well as for various J levels in the parity forbidden bands (ns²np⁶ → ns²np⁵(n + 1)p) for argon and neon.