Note: electrochemical etching of sharp iridium tips

We describe an etching procedure for the production of sharp iridium tips with apex radii of 15-70 nm, as determined by scanning electron microscopy, field ion microscopy, and field emission measurements. A coarse electrochemical etch followed by zone electropolishing is performed in a relatively harmless calcium chloride solution with high success rate.     

Safe fabrication of sharp gold tips for light emission in scanning tunnelling microscopy

Gold is the optimal tip metal for light emission in scanning tunnelling microscopy (LESTM) under ambient conditions. Sharp Au-tips of 10 nm radius were produced reliably using a safe, two-step etching method in 20% (w/w) CaCl₂ solution. Previous CaCl₂-based methods have tended to produce blunter tips, while other etching techniques that do produce sharp Au-tips, do so with the use of toxic or hazardous electrolytes. The tips are characterised using scanning electron microscopy and their efficacy in LESTM is evidenced by high-resolution, simultaneous topographic and photon mapping of Au(1 1 1)- and polycrystalline Au-surfaces. Spectra of the optical emission exhibit only one or two peaks with etched tips in contrast to the more complex spectra typical of cut tips; this feature, together with the highly symmetric geometry of the tips, facilitates a definitive analysis of the light emission process.     

Effects of process parameters on the electrochemical etching of sharp metallic tips with an attached mass

The electrochemical etching of a metal wire with an attached mass at the end of the immersed wire is a new technique to enhance the yield rate of sharp tips. Unlike conventional electrochemical etching, the yield rate of sharp tips with subhundred nanometer apex could be increased up to around 60% with the attached mass method. In this article, the effects of the magnitude of attached mass and the taping material used for attachment on the yield rate and tip shape are investigated. Also, the variation of tip shape with respect to the temporal shape of applied electric field, constant or pulsed dc, is examined.     

Note: In situ cleavage of crystallographic oriented tips for scanning probe microscopy

We report an in situ method of preparing tips for scanning probe microscopy (SPM). Oriented single-crystal nickel oxide (NiO) rods were diced, using a wafer saw, to prepare artificial breaking points. Two geometries, a single rod and a two-sided cut rod were fabricated. The cleavable tips were mounted to a force sensor based on a quartz tuning fork and cleaved using the coarse approach of the SPM. Atomically resolved force microscopy images of NiO (001) were taken with these NiO tips.     

Recrystallization of tungsten wire for fabrication of sharp and stable nanoprobe and field-emitter tips

Atomically sharp tungsten tips made from single crystal tungsten wire are superior to those made from cold-drawn polycrystalline wire but are rarely used due to their high price. We have devised a method of obtaining highly crystalline tungsten wire by recrystallizing cold-drawn wire. The effect of various heat treatments on the wire microstructure was observed using scanning electron microscopy and x-ray diffraction. A dramatic difference in the shapes of tips etched from cold-drawn and recrystallized wires was observed using transmission electron microscopy. The described annealing process is an inexpensive alternative to using single crystal wires.     

Fabrication of gold tips by chemical etching in aqua regia

We present a method to produce sharp gold tips for applications in apertureless near-field optical microscopy and spectroscopy. Thin gold wires are tapered by chemical etching in aqua regia, covered by an isooctane protective layer. Tips with apical radii of curvature of <50 nm are obtained with a 40% yield. The tip performances have been checked by shear-force imaging of amyloid fibrils samples and compared to optical fiber probes. The analysis of the tip morphology, carried out by scanning electron microscopy, shows the existence of two different etching processes occurring in bulk and at the liquid-liquid interface. A simple analytical model is presented to describe the dynamics of the tip formation at the liquid-liquid meniscus interface that fits remarkably well the experimental results in terms of tip shape and length.     

Comprehensive surface analysis of hydrophobically functionalized SFM tips

Tip-sample interactions have been of interest since the early development of the scanning force microscope. Investigations of interfacial interactions at the molecular level are of importance for fundamental studies of bi-molecular interactions and for possible applications in biomedical research and industrial settings. By engineering the surface chemical properties of the SFM probes, specific force interactions may be measured. However, as these modification schemes become more widely applied, detailed chemical analysis of the modified cantilever surfaces becomes crucial. In this paper, we describe two approaches to coat SFM cantilevers with hydrophobic coatings: a silanization protocol and ratio frequency plasma enhanced chemical vapor deposition.     

高表面质量弯曲件的试验研究

弯曲件成形时弯曲毛坯和凹模之间的相对摩擦是表面擦伤原因。通过对弯曲工艺及模具的试验研究,确定组合模具及其工艺参数,避免弯曲件的擦伤,减小弯曲回弹,保证产品质量,降低生产成本。特别是弯曲一些艺术性要求高、外表面必须保证美观的弯曲件时,这种弯曲件模具结构,更显示出技术经济优越性。     

Note: A scanning electron microscope sample holder for bidirectional characterization of atomic force microscope probe tips

A novel sample holder that enables atomic force microscopy (AFM) tips to be mounted inside a scanning electron microscopy (SEM) for the purpose of characterizing the AFM tips is described. The holder provides quick and easy handling of tips by using a spring clip to hold them in place. The holder can accommodate two tips simultaneously in two perpendicular orientations, allowing both top and side view imaging of the tips by the SEM.     

Note: Circuit design for direct current and alternating current electrochemical etching of scanning probe microscopy tips

We present control circuits designed for electrochemically etching, reproducibly sharp STM probes. The design uses an Arduino UNO microcontroller to allow for both ac and dc operation, as well as a comparator driven shut-off that allows for etching to be stopped in 0.5-1 μs. The Arduino allows the instrument to be customized to suit a wide variety of potential applications without significant changes to hardware. Data is presented for coarse chemical etching of 80:20 platinum-iridium, tungsten, and nickel tips.     

Note: high capacity digital laser beam steering system

The combination of liquid crystal cells with polarizing cube beam splitters has been used to direct a beam of light to multiple directions. The polarization at each beam splitter is controlled by applying a signal to a corresponding liquid crystal cell. Ten cascaded stages have deflected a HeNe laser beam to 1024 digitally selectable angles.     

Field emission techniques for studying surface reactions: applying them to NO-H2 interaction with Pd tips

The adsorption of NO and its reaction with H₂ over Pd tips were investigated by means of field ion microscopy (FIM) and pulsed field desorption mass spectrometry (PFDMS) in the 10⁻³ Pa pressure range and at sample temperatures between 400 and 600 K. By varying the H₂ partial pressure while keeping the other control parameters constant, the NO+H₂ reaction over Pd crystallites is shown to exhibit a strong hysteresis effect. The hysteresis region narrows with increase in temperature and the H₂ pressures delimiting this hysteresis decrease as well. Abrupt transformations of the micrographs are observed by FIM from bright to dark patterns and vice versa. These transformations define the hysteresis region. The collected data allow establishing a novel kinetic phase diagram of the NO+H₂/Pd system within the range of temperatures and pressures indicated. The observed features are correlated with a local chemical analysis by means of field pulses. NO⁺ seems to be the dominating imaging species under all conditions. At high relative H₂ pressures (the “hydrogen-side”), H atoms seem to diffuse subsurface. This process is blocked at lower H₂ pressure (the “NO-side”) due to NO_ad and O_ad accumulation on the surface. Probe-hole measurements with field pulses indicate that the Pd surface undergoes oxidation as revealed by the occurrence of PdO₂⁺ species in the mass spectra.     

Study of surface quality in high speed turning of Inconel 718 with uncoated and coated CBN tools

Inconel 718 is known to be among the most difficult-to-machine materials due to its special properties which cause the short tool life and severe surface damages. The properties, which are responsible for poor machinability, include rapid work hardening during machining; tendency to weld with the tool material at high temperature generated during machining; the tendency to form a built-up edge during machining; and the presence of hard carbides, such as titanium carbide and niobium carbide, in their microstructure. Conventional method of machining Inconel 718 with cemented carbide tool restricts the cutting speed to a maximum 30?m/min due to the lower hot hardness of carbide tool, high temperature strength and low thermal conductivity of Inconel 718. The introduction of new coated carbide tools has increased cutting speed to 100?m/min; nevertheless, the time required to machine this alloy is still considerably high. High speed machining using advanced tool material, such as CBN, is one possible alternative for improving the productivity of this material due to its higher hot hardness in comparison with carbide tool. This paper specifically deals with surface quality generated under high speed finishing turning conditions on age-hardened Inconel 718 with focus on surface roughness, metallographic analysis of surface layer and surface damages produced by machining. Both coated and uncoated CBN tools were used in the tests, and a comparison between surfaces generated by both tools was also discussed.     

Cell surface labelling with gold colloid particulates: the use of avidin and staphylococcal protein A-coated gold in conjunction with biotin and fc-bearing ligands

Procedures for preparing gold colloid particles stabilized with either avidin or protein A are described. Methods of using these general utility tracers for localizing biotinylated and fc bearing immunoglobulins are outlined and, as examples of the way in which these methods can be applied, procedures for identifying epidermal growth factor receptors and surface fibronectin on ovarian granulosa cells are described.     

Note: A high dynamic range, linear response transimpedance amplifier

We have built a high dynamic range (nine decade) transimpedance amplifier with a linear response. The amplifier uses junction-gate field effect transistors (JFETs) to switch between three different resistors in the feedback of a low input bias current operational amplifier. This allows for the creation of multiple outputs, each with a linear response and a different transimpedance gain. The overall bandwidth of the transimpedance amplifier is set by the bandwidth of the most sensitive range. For our application, we demonstrate a three-stage amplifier with transimpedance gains of approximately 10(9)Ω, 3 × 10(7)Ω, and 10(4)Ω with a bandwidth of 100 Hz.     

Note: Vector network analyzer-ferromagnetic resonance spectrometer using high Q-factor cavity

A ferromagnetic resonance (FMR) spectrometer whose main components consist of an X-band resonator and a vector network analyzer (VNA) was developed. This spectrometer takes advantage of a high Q-factor (9600) cavity and state-of-the-art VNA. Accordingly, field modulation lock-in technique for signal to noise ratio (SNR) enhancement is no longer necessary, and FMR absorption can therefore be extracted directly. Its derivative for the ascertainment of full width at half maximum height of FMR peak can be found by taking the differentiation of original data. This system was characterized with different thicknesses of permalloy (Py) films and its multilayer, and found that the SNR of 5 nm Py on glass was better than 50, and did not have significant reduction even at low microwave excitation power (-20 dBm), and at low Q-factor (3000). The FMR other than X-band can also be examined in the same manner by using a suitable band cavity within the frequency range of VNA.     

针对高速加工的新材质等级设计

文章阐述了一种针对高速切削金属时提高刀具耐磨性与抗塑性变形能力的涂层硬质合金材质等级设计的新进展。在深入了解涂层材料磨损特性的基础上,介绍了一种新的涂层设计。这种新涂层将一种改善韧性的功能材质基体与刀具的切削刃强度组合在一起。     

Note: Development of a high resolution six-degrees-of-freedom optical vibrometer for precision stage

A high resolution six degrees of freedom (6-DOF) optical vibrometer is proposed. 6-DOF vibrations can be simultaneously measured using the proposed optical vibrometer, which reduces measurement time and number. The performance of the proposed vibrometer is verified by experiments. The results show that the accuracy of the proposed optical vibrometer is ±30 nm∕200 nm and ±0.04 arcsec∕0.1 arcsec at 1000 Hz.     

Note: Quantitative (artifact-free) surface potential measurements using Kelvin force microscopy

The measurement of local surface potentials by Kelvin force microscopy (KFM) can be sensitive to external perturbations which lead to artifacts such as strong dependences of experimental results (typically in a ～1 V range) with KFM internal parameters (cantilever excitation frequency and/or the projection phase of the KFM feedback-loop). We analyze and demonstrate a correction of such effects on a KFM implementation in ambient air. Artifact-free KFM measurements, i.e., truly quantitative surface potential measurements, are obtained with a ～30 mV accuracy.     

Note: Synchronized stress-strain measurements in dynamic loading at high pressure using D-DIA

A new data collection protocol for forced oscillation experiments using a multianvil high pressure device is reported. We derive the stress of the sample at high pressure and temperature from synchrotron x-ray diffraction that is synchronized with sample strain measurements from x-ray radiographs. This method yields stress directly from the sample rather than a stress proxy. Furthermore, the diffraction pattern yields useful information concerning time evolution of structurally related phenomena. Here we illustrate some of these possibilities with high pressure experimental data.