Beam Deflection Techniques Research Articles

Isothermal and non-isothermal transport properties of diluted fullerene binary and ternary aromatic solvent mixtures.

We present mass transport properties of C60 fullerene in five aromatic solvents, methylnaphthalene, toluene and three xylene isomers. Optical beam deflection and thermogravitational column techniques were used to determine molecular diffusion, thermodiffusion and Soret coefficients. All thermo-optical properties necessary to determine the abovementioned coefficients are also given at a mean working temperature of 298.15 K and an atmospheric pressure of 0.101 MPa. The magnitude of all transport properties is governed by the molecular weight ratio. In the particular case of the isomers, experiments revealed that movement under isothermal conditions (described by molecular diffusion) is dominated by density, while under non-isothermal conditions viscous forces affect the displacement (thermodiffusion depends on the dynamic viscosity). In the case of the Soret coefficients, as a combination of both, density is the dominant parameter and also the moment of inertia.

Detection of temporary capillary stability in EB beam-deflection techniques using X-ray self-illumination

A deeper understanding of the temporal behaviour of capillaries enables the improvement of modern beam welding processes, e.g. the application of the multi-bath or multi-process technique in electron beam welding. The temporal capillary behaviour in an Electron Beam (EB) multi-bath welding process can be analysed at different beam deflection frequencies by means of secondary X-ray. This is visualised by X-rays which are generated during beam-material interaction in the capillary and can be visualised as an upside-down image on a scintillator screen via a pinhole camera. The analysis of the high-speed images allows conclusions regarding the inertia of a temporarily unheated EB capillary. This paper shows that with increasing deflection rate the collapse of capillary decreases while at a deflection rate of 1000 Hz no collapse in capillary depth can be detected.

Recent Progress and Applications of Thermal Lens Spectrometry and Photothermal Beam Deflection Techniques in Environmental Sensing.

This paper presents recent development and applications of thermal lens microscopy (TLM) and beam deflection spectrometry (BDS) for the analysis of water samples and sea ice. Coupling of TLM detection to a microfluidic system for flow injection analysis (μFIA) enables the detection of microcystin-LR in waters with a four samples/min throughput (in triplicate injections) and provides an LOD of 0.08 µg/L which is 12-times lower than the MCL for microcystin-LR in water. μFIA-TLM was also applied for the determination of total Fe and Fe(II) in 3 µL samples of synthetic cloudwater. The LODs were found to be 100 nM for Fe(II) and 70 nM for total Fe. The application of µFIA-TLM for the determination of ammonium in water resulted in an LOD of 2.3 µM for injection of a 5 µL sample and TLM detection in a 100 µm deep microfluidic channel. For the determination of iron species in sea ice, the BDS was coupled to a diffusive gradient in the thin film technique (DGT). The 2D distribution of Fe(II) and total Fe on DGT gels provided by the BDS (LOD of 50 nM) reflected the distribution of Fe species in sea ice put in contact with DGT gels.

Study of pulsed laser-induced heating in bio-plasmonic solution using combined photoacoustic and probe beam deflection technique: Thermoacoustic effects

We describe studies of the interaction of a pulsed Nd:YAG laser with bovine serum albumin (BSA) solution (i.e., S0) and S0 containing gold nanourchin (GNU) (i.e., S1: S0 + 0.1 ml GNU) using combined photoacoustic (PA) and probe beam deflection (PBD) techniques. The changes in absorbance and chemical bonds are studied by UV–Vis and near-FTIR spectroscopy. The results showed a decrease in absorbance of the bio-plasmonic solution, which further decreased by increasing the concentration. The PA pressure increased with fluence in the order of GNU > S0 > S1, and all exhibited a non-linear response at ≈9.5 J cm−2and reached a maximum at 12.5 J cm−2. No PBD was observed in S0 indicating the role of GNU in producing the heating effect. ∂n/∂T increased in the order of S2 > S1 > S0, respectively, where S2 is (S0 + 0.2 ml GNU). The absorbance of S0 and S1 increased after heating due to protein denaturation. For S1, surface-enhanced FTIR showed an increase in the intensity of most bands between 6320 and 6630 cm−1, and the band at 5264 cm−1, which likely corresponds to β-sheet structure, significantly diminished after heating. The collapse of cavitation and plasma shock waves produced significant acoustic transients, hence some photomechanical effects. The acoustic energy released after the collapse of bubbles at 1.8 and 12.5 J cm−2was calculated to be ≈140 μJ and 7 mJ, respectively, corresponding to 4% and 28% of the input optical energy being converted to sound energy in the early phase of the expansion.

Influence of electron beam deflection techniques used during the cladding process on the wear and corrosion behaviour of cobalt‐based protective coatings on austenitic stainless steel

AbstractThe present work aims to improve the wear resistance of the austenitic stainless steel X6CrNiMoTi17‐12‐2. In view of the potential use of this alloy, however, corrosion resistance should be maintained where possible. An electron beam surface treatment (cladding) was performed, and the cobalt‐based alloy Stellite® 12 was used as the wear‐resistant material. The presented results show the effects of several electron beam oscillation figures during the cladding process with regard to layer bonding, microstructure formation and hardness. The surface hardness achieved was 576±18 HV 0.3, almost three times higher than that of the base material (203±3 HV 0.3). The scratch energy density – which represents the resistance to abrasive wear – could be increased by a factor of 1.5. Under abrasive‐adhesive stress loading conditions, the determined wear volume decreased by a factor of almost 5. Based on the corrosion investigations carried out, it was possible to prove that in comparison to the base material, the tendency towards pitting corrosion could be almost completely suppressed.

In Situ Characterization of Nanostructured Electrode Materials for Energy Conversion and Storage, Using Probe Beam Deflection Techniques

Nanostructured conductive materials of large surface area which are important in many areas of energy conversion and storage, including supercapacitors and fuel cells. While electrochemical techniques (e.g. cyclic voltammetry) assess the charge transfer processes at the electrode interface, the ion exchange process could only be inferred. Techniques of ion exchange determination, such as the electrochemical quartz crystal microbalance (EQCM) are of difficult application to porous electrodes since it requires fixing the porous material to the oscillating crystal. On the other hand, the techniques that monitor ion fluxes outside the electrode surface are able to study the actual ion exchange between a porous electrode and the electrolyte. Among them, Probe Beam Deflection (PBD) is a technique highly suitable to study porous electrodes.[1] The method uses a laser beam travelling parallel to the electrode surface which is refracted by the refractive index gradient associated with the flux of soluble species perpendicular to the electrode, at the center of the laser beam. Since the detection of beam position is optoelectronic, fast (ms) signals can be measured, unlike EQCM, allowing detecting transient phenomena. Since the flux is directly proportional to the surface area (like the current) the ratio of surface area to geometric pathlength (width of the electrode) assures large signal for porous electrodes. In this report, the study of different electrode materials using Probe Beam Deflection techniques is described. After a qualitative exploration using cyclic deflectometry, a continuous mass transport model is used to quantitatively evaluate the chronodeflectometric response.[2] First, the study of different porous glassy carbon materials is described. Then, PBD is applied to study mesoporous ordered Pt materials active in direct methanol fuel cells.[3] Finally, thin films of mesoporous oxides decorated with Au nanoparticles,[4] are investigated. The potential of minimum charge (PMC) can be determined and compared with the value measured by AC Impedance. Besides, transient phenomena like pH changes or effects on the coupled chemical reactions inside the pores can be easily detected. Therefore, a better understanding on the mass transfer in porous electrodes is obtained.

Ground measurements of dcmix 4 project Fullerene based nanofluid

This work presents first on ground measurements of DCMIX 4 project ternary nanofluid Fullerene, 1,2,3,4-tetrahydronaphtalene and Toluene. Transport properties have been measured by Thermogravitational, Optical Digital Interferometry and Optical Beam Deflection techniques for concentration analysed in DCMIX 4 project, which refers to 0.0007 – 0.60 – 0.3993 and other fullerene concentrations around this value. Various thermophysical and optical properties which are necessary to determine thermodiffusion coefficients have been also measured.

Stroboscopic Space Tag for Optical Time-Resolved Measurements with a Charge Coupled Device Detector

Time-resolved measurements are extensively employed in the study of light–matter interaction at the nanoscale such as the exciton dynamics in semiconductors or the ultrafast intraband transitions in metals. Importantly, single-photon correlation, quantum state tomography, and other techniques devoted to the characterization of quantum optics systems rely on time-resolved experiments, whose resolution which is bound to the time response of the detector and related electronics. For this reason, multiplexing or beam deflection techniques have been recently proposed to overcome the detector resolution and thus measure the final photon distribution characteristics. Taking advantage of both strategies, in this work we present a simple method to obtain time-resolved light transients independently on the detector response. The method is based on the stroboscopic synchronization of a given optical signal after spatial tag of its time response. To illustrate the potential of the approach, we present a simple setup ...

Studies on the influence of electron beam deflection techniques on the quality and properties of surface alloyed cast Al material with Cu based additive

Electron beam alloying (EBA) using a Cu-36Ni additive was examined with the specific aim of improving the hardness and wear behaviour of a cast Al alloy (AlSi10Mg). To this end, investigations were carried out using different beam deflection techniques to identify the correlations between the area of instantaneous energy distribution input and the layer characteristics that resulted, such as surface deformation, layer geometry, hardness gradient and the homogeneity of the alloyed microstructure. The average hardness of the EBA layers was defined varied in the range of from 200 to 700HV0.5 by adjusting the energy input and the alloyed content respectively. Detailed investigations of the EBA layer microstructures using EDX and XRD analyses detected α-Al, primary Si and a number of intermetallic phases. The higher the content of intermetallic phases, the higher was the layer hardness.The wear behaviour under abrasive test conditions was studied by scratch testing with a constant load of 20N, and under adhesive conditions by unlubricated pin-on-disc testing with a normal load of 20N over a sliding distance of 50m.EBA layers with an average hardness of approx. 400HV0.5 delivered the best results with respect to both the layer quality generated (phase distribution, cracks and pores) and the resulting wear behaviour.

Directly monitor protein rearrangement on a nanosecond-to-millisecond time-scale

In order to directly observe the refolding kinetics from a partially misfolded state to a native state in the bottom of the protein-folding funnel, we used a “caging” strategy to trap the β-sheet structure of ubiquitin in a misfolded conformation. We used molecular dynamics simulation to generate the cage-induced, misfolded structure and compared the structure of the misfolded ubiquitin with native ubiquitin. Using laser flash irradiation, the cage can be cleaved from the misfolded structure within one nanosecond, and we monitored the refolding kinetics of ubiquitin from this misfolded state to the native state by photoacoustic calorimetry and photothermal beam deflection techniques on nanosecond to millisecond timescales. Our results showed two refolding events in this refolding process. The fast event is shorter than 20 ns and corresponds to the instant collapse of ubiquitin upon cage release initiated by laser irradiation. The slow event is ~60 μs, derived from a structural rearrangement in β-sheet refolding. The event lasts 10 times longer than the timescale of β-hairpin formation for short peptides as monitored by temperature jump, suggesting that rearrangement of a β-sheet structure from a misfolded state to its native state requires more time than ab initio folding of a β-sheet.

Ethanol extract of propolis as a protective coating for mild steel in chloride media

The anticorrosion performance of commercial extract of ethanolic propolis (EP)-coated mild steel samples immersed in a 3.5% w/v NaCl in neutral and near neutral media was evaluated by classical electrochemical and electrochemical probe beam deflection techniques. The functional groups and major components of the extract were identified by Fourier transform infrared spectroscopy and high-performance liquid chromatography, respectively. The extract and the major constituent identified in the extract, 3,5-diprenyl-4-hydroxycinnamic acid (DHCA), are poorly hydro-soluble in a neutral medium. The bare and coated carbon steel surfaces were characterized by scanning electron microscopy and atomic force microscopy before and after a saline immersion. The electrochemical response of the coated electrodes was compared with bare mild steel electrodes and all qualitative and quantitative data obtained supported the hypothesis that EP is a potential mild steel corrosion inhibitor. Although several flavonoids are known to have remarkable antioxidant properties and be effective metal corrosion inhibitors, this work is pioneering in its evaluation of the inhibitory capacity of a natural product whose main constituent is DHCA.

Thermo-mechanical transduction suitable for high-speed scanning probe imaging and lithography

Microelectromechanical systems (MEMS) with integrated read-out and actuation are very useful tools for a wide variation of applications, especially in scanning probe microscopy (SPM) and lithography (SPL). They avoid the use of conventional optical beam deflection techniques or external excitation and are suitable for massively parallel scanning probe solutions and biochemical sensors. Such arrays of beams offer an increased throughput to scan large areas in SPM and SPL. However, the fabrication technology of such complex MEMS requires careful design of all components. This paper presents a comparison between analytical, numerical and experimental data of a cantilever with integrated thermal actuator and piezoresistive sensor, suitable for fast SPM and SPL. The focus of this work lies on the efficiency of the actuator, to achieve a high static displacement, which is required for an array operation. To maximize this displacement, two material compositions for a varying geometry of the beam's layers are analyzed. With a scanning electron microscope and a laser vibrometer an increased displacement of the beam about 10μm can be presented, which is in a good agreement with our theoretical predictions.

Combined Surface Treatment of Electron Beam Alloying and PVD Hard Coating for Al Alloys

Due to their typically high hardness, excellent resistance against wear, and their low coefficient of friction, Physical Vapor Deposition (PVD) hard coatings are used on steels for a wide range of tools and components. Currently, however, the potential for wear protection of Al alloy components cannot be exploited. The thin PVD layers tend to collapse and disintegrate due to plastic deformation of the soft base material. Present research is focused on electron beam (EB) surface alloying, using Co-based additives to increase the surface hardness of the Al base material, producing an improved supporting effect for PVD coatings. The influence of different beam deflection techniques and EB parameters on the microstructure and hardness of alloyed layers was investigated. The properties of the duplex composite layers produced are strongly dependent on the thermal stability of the EB alloyed layers (type and amount of intermetallic compounds, coarsening effects) which are affected by the temperature-time cycle of the PVD process. This will be discussed by means of SEM and EDX investigations in correlation with XRD analysis. Measurements using scratch test with increasing load result in critical load values for the combined treatment that are 3 to 5 times higher when compared to only PVD-coated base material.

Electroanalysis using modified hierarchical nanoporous carbon materials

The role of the electrode nanoporosity in electroanalytical processes is discussed and specific phenomena (slow double layer charging, local pH effects) which can be present in porous electrode are described. Hierarchical porous carbon (HPC) materials are synthesized using a hard template method. The three dimensional carbon porosity is examined using scanning electron microscopy on flat surfaces cut using a focused ion beam (FIB-SEM). The electrochemical properties of the HPC are measured using cyclic voltammetry, AC impedance, chronoamperometry and Probe Beam Deflection (PBD) techniques. Chronoamperometry measurements of HPC seems to fit a transmission line model. PBD data show evidence of local pH changes inside the pores, during double layer charging. The HPC are modified by in situ (chemical or electrochemical) formation of metal (Pt/Ru) or metal oxide (CoOx, Fe3O4) nanoparticles. Additionally, HPC loaded with Pt decorated magnetite (Fe3O4) nanoparticles is produced by galvanic displacement. The modified HPC materials are used for the electroanalysis of different substances (CO, O2, AsO3(-3)). The role of the nanoporous carbon substrate in the electroanalytical data is evaluated.

Liquid phase surface engineering of aluminium alloys using novel electron beam deflection techniques and its influence on microstructure: property relationships

AbstractThe application of lightweight materials such as aluminium alloys, especially in systems stressed due to tribological contacts, calls for an additional modification of functional surfaces according to the loading conditions. Not least because of a modern generation of beam deflection techniques available, electron beam (EB) liquid phase surface treatment is a possible and innovative solution for these requirements. The modification of microstructure and properties of the surface layers (0·5–6·2 mm in thickness) is caused by rapid solidification and cooling by self-quenching, whereas layer properties (hardness, friction and wear behaviour) can be improved significantly, especially in combination with the use of additional elements (Co, Cu, Ni) and/or hard particles (WC) during local EB processing (surface alloying/dispersion hardening). Experimental results show 2–7 times higher hardness and scratch energy values as well as up to 20 times lower wear rates in combination with decreased friction coef...

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century Part 15 – Progress in surface heat treatment using electron beam surface hardening

By using high frequency beam deflection techniques it is possible to carry out highly productive electron beam (EB) surface treatment. As a result of comprehensive investigations about the influence of EB parameters on structure and properties of the material in connection with EB hardening of steels and cast irons over the last 25 years, very interesting industrial applications are available now. The paper deals with the state of the art in this field.

A novel way to maintain resorcinol–formaldehyde porosity during drying: Stabilization of the sol–gel nanostructure using a cationic polyelectrolyte

The formation of monolithic porous carbon having a BET surface area of ca. 725 m 2/g is achieved by carbonization of a resorcinol/formaldehyde (RF) resin prepared in the presence of a cationic polylectrolyte (polydialyldimethylammonium chloride, PDADMAC). The porosity of the resin is maintained during air drying due to the stabilizing effect of a cationic polyelectrolyte on the sol–gel nanostructure. While carbon made of RF resins prepared in the presence of cationic polyelectrolyte show a large surface area, those prepared in the presence of a negatively charged polyelectrolyte (poly(styrenesulfonate), PSS), a neutral hydrophylic polymer (poly(vinyl alcohol), PVA) or in the absence of polymeric additives renders carbon materials having negligible surface areas (<10 m 2/g). It seems that positively charged polymer stabilizes the negatively charged resin nanoparticles, suggesting a new mechanism of action for cationic species in porous RF formation. The method simplifies greatly the fabrication of porous carbon by making unnecessary to use complex (e.g. supercritical) drying procedures. It also does not require long curing times and cumbersome solvent exchange. Avoiding the use of organic solvents makes the process friendlier to the environment. The carbon material presents large electrochemical specific capacitance ( ca. 210 Fg −1 in acid media and 110 Fg −1 in neutral media) making it suitable for supercapacitor applications. The ion exchange properties, related with the double layer charging/discharging processes are investigated using Probe Beam Deflection techniques.

Duplex surface layer treatment of Al alloy: electron beam alloying and plasma nitriding

AbstractAl alloys offer a high potential as lightweight construction materials due to their low density, specific strength and processing properties. However, the field of application is limited by their low hardness and poor wear properties. Duplex surface treatment combining electron beam (EB) alloying and plasma nitriding offers one possibility to produce hard and wear resistant surface layers on Al alloys. The EB alloyed surface layer acts as supporting layer for the hard AlN coating so that the load bearing capacity can be enhanced. In the present study duplex treatment of Al-5083 (AlMg4·5Mn0·7) Al alloy has been investigated. Before the EB treatment alloying material deposition was carried out by atmospherically plasma spraying. Various sandwich layers based on Al and Fe respectively, have been applied. Different beam deflection techniques have been tested and their effect on surface deformation, microstructure and hardness was evaluated. Plasma nitriding was carried out in order to evaluate the nit...

In Situ Calorimetry at Metal−Electrode Liquid Electrolyte Interfaces As Monitored by Probe Beam Deflection Techniques

A probe beam deflection method that allows for the heat generated or absorbed during an interfacial proces to be determined in situ is herein described. These optical measurements are performed using a collimate laser beam propagating parallel to the interface through the back of a flat, optically transparent ZnSe crystal that supports a very thin film of a metal electrode in contact with the electrolyte solution. Analysis a experimental data collected for a Au electrode in sulfuric acid aqueous solutions using numerical simulation were found to be consistent with the release of ~375 kJ/mol upon formation of a monolayer of Au oxide This value is very similar to the value observed using the same methodology for the reduction of the A oxide layer under otherwise the same experimental conditions.

Probe beam deflection studies of nanostructured catalyst materials for fuel cells

Probe beam deflection (PBD) techniques, both as cyclic voltadeflectometry (CVD) and chronodeflectometry (CD), were applied for the first time to the study of the electrochemistry of nanostructured Pt materials which are commonly used as electrocatalysts in fuel cells. The electrochemical surface reactions, including faradaic processes, double layer charging and specific anion adsorption were easily detected. Quantitative analysis of the chronodeflectometric data made possible to elucidate the dynamics of double layer charging in such materials and to determine the potential of zero charge (pzc) of the metal present either as a monolithic mesoporous material or as metal nanoparticles supported on carbon. The electro-oxidation of CO, adsorbed on nanostructured Pt, was also studied by CVD and CD being able to detect the formation of CO2 and H3O+ related with the nucleation and growth process which controls the rate of CO stripping. The interplay of Pt oxide formation and COad electrooxidation, both in potential and time, was detected indicating possible application of the technique to other electrocatalysts.