A new method for high-resolution quantitative measurement of the dielectric function by using scattering scanning near-field optical microscopy (s-SNOM) is presented. The method is based on a ...calibration procedure that uses the s-SNOM oscillating dipole model of the probe-sample interaction and quantitative s-SNOM measurements. The nanoscale capabilities of the method have the potential to enable novel applications in various fields such as nano-electronics, nano-photonics, biology or medicine.
A new composite matrix was developed for a cutting tool based on tungsten carbide ligated with cobalt (WC-Co) using sintering technique. The admixtures of niobium carbide, tantalum carbide, and ...titanium carbide with the WC-Co matrix aim to inhibit the grain growth of WC and to promote covalent bonding at the interface. The modified WC-Co tools were coated with titanium nitride and titanium carbonitride layers by CAE-PVD technique. To substantiate the performances of the new coating-substrate systems, we have performed X-ray diffraction, atomic force microscopy, and scratch test measurements to estimate: phase content, average crystallite size, average texture coefficient, residual stress level, coating thickness, average roughness, square mean root, fractal dimension, cohesive adhesion, and adhesive adhesion. The results enable the in-depth understanding of the coating growth mechanisms and provide an objective evaluation of the coatings adhesion to the new cutting tools matrix. The results provide evidence to support the potential of TiN and TiCN coatings to enhance the working performances of the composite WC-Co cutting tools and to differentiate their properties. TiCN coating is shown to be superior to TiN coating in terms of adhesion and thus represents a better alternative for coating the modified WC-Co composite matrix.
The dependence of the near-field signal on the dielectric function of a specific material proposes scattering-type near-field optical microscopy (s-SNOM) as a viable tool for material ...characterization studies. Our experiment shows that specific material identification by s-SNOM is not a straightforward task as parameters involved in the detection scheme can also influence material contrast measurements. More precisely, we demonstrate that s-SNOM contrast in a pseudo-heterodyne detection configuration depends on the oscillation amplitude of the reference mirror and that for reliable measurements of the contrast between different materials this aspect needs to be taken into consideration.
In this work, 2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphine (OEP) in its free base form and metalated with iron (III) chloride (FeOEP), magnesium(II) (MgOEP) and cobalt(II) (CoOEP) have been used to ...fabricate Langmuir–Blodgett (LB) thin films. Using the surface pressure–surface area (
Π–
A) isotherm graphs optimum conditions for thin film deposition have been determined and by changing the deposition parameters various thin films have been deposited. Quartz Crystal Microbalance (QCM) system was used to investigate their gas sensing performances during exposure to Volatile Organic Compounds (VOCs) including chloroform, benzene and toluene. The surface properties have been investigated using Atomic Force Microscopy (AFM) and analyzed together with the QCM results to understand the effect of the surface properties on gas sensing mechanism. It is observed that larger surface area leads to higher response in gas sensing applications in terms of resonance frequency change.
The fabrication and nonlinear optical imaging of ~ 5-nm-sized lead sulfide (PbS) nanoscale particles prepared in a water-soluble polymer matrix is reported. The two photon excitation fluorescence ...(TPEF) studies (using Ti:Sapphire laser, λ ex ~ 706 nm, P = 400 mW, pulse ~ 80 fs) clearly show the foremost band-edge and asymmetric trap-related emissions. The chain-like organization of PbS nanoparticles was evident from the electron microscopy studies, and the impression from a cluster of nanopatterns was observable through laser scanning confocal microscopy. We have observed adequate correspondence between the TPEF spectra-based nonlinear optical images and spots corresponding to PbS nanoparticle assemblies. In addition, the PbS nanoparticles that are capable of producing strong second harmonic signals were efficiently imaged along the forward direction of the nonlinear microscopy. Investigation of two photon absorption processes along with the second-harmonic-generated imaging indicates the possibility of using the nanoscale particles in single molecule fluorescence spectroscopy, biomolecular labeling, and/or imaging applications.
Carbon fiber reinforced plastics (CFRP) have become an indispensable part of modern life. CFRP materials continue to be used in a large number of applications ranging from aerospace systems to ...automotive, industrial and consumer products. CFRP have evolved both in reinforcement and matrix. The epoxy resin was the most usually matrix for CFRP. The reliability of these materials is essential, especially when it comes to safety-relevant components. The service life of CFRP components is affected by aging processes or improper use. Nondestructive evaluation methods which can be applied for examination carbon/epoxy laminates, manufactured by autoclave processing method with different ply stacking sequences 08 and (45/0)2s are presented. The samples were realized from 4 plates of carbon-epoxy manufactured at the Faculty of Mechanical Engineering, University of Ljubljana, Slovenia. The paper present influence of thermal treatment and stacking sequence on damage delamination's due to impact about mechanical properties. Ultrasound and electromagnetic nondestructive evaluation methods are used for good localization of damage and characterization composite materials and other techniques can provide complementary information once the damage location is known.
Silicon carbide has been identified as a potential inert matrix candidate for advanced fuel. In this work, the growth of SiC thin films by pulsed laser deposition is reported. The stoicheometry and ...thickness of deposited films was investigated by non-Rutherford backscattering spectrometry. The influence of the deposition parameters, i.e. substrate temperature and laser fluence on the structure, morphology and optical properties of the deposited thin layers was studied. It was found that polycrystalline SiC thin films with uniform surface morphology were obtained at 873
K.
The paper presents the architecture of a new type of electromagnetic sensor in 2D structure designed and made in order to estimate the location of a discontinuity below the surface of a conductive ...material. The use of 2D emission reception architecture in configuration of 5x5 identical reception sensors excited by a surrounding emission coil is proposed. The analysis follows the way in which one or more linear fatigue cracks that intersect can affect the eddy current answers and the electromotive force induced in the reception coils. The study of the dependence of the field distribution on the number and position of the reception coils against the discontinuity was carried out using FDTD. Spatial resolution has been improved using a known super resolution algorithm. The 2D structure was tested for the detection of subsurface discontinuities induced in Al2024 samples subjected to cyclic loading.
The models designed CAD/CAM were loaded into the simulator to analyze the characteristics of the experimental devices attached. The array of sensors with unconventional architecture with ...reconfigurable unit cells (UCs) was topologically optimized, establishing the opening angle of the cell, the active surface, the geometry of the structure of the areas starting from the idea that the resonance frequency should be within the range of ISM frequencies. The simulations and determinations of test parameters of UC geometry are used for realization of arrays with reconfigurable shapes having the same aperture angle that can be used as wireless sensors for pressure detection.
A confocal laser scanning microscope modified to acquire optical beam induced current images is used to investigate a novel type of semiconductor lasers—photonic quantum ring lasers. We compare the ...lasing and the photoinduced current images of the structures and analyze their behavior when changing the excitation wavelength. We report the optimal excitation conditions in terms of excitation laser wavelength for collecting the highest photocurrent signal and hence highlighting the photonic quantum ring behavior of the lasers.
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