Search results for "Microscope"
showing 10 items of 1412 documents
Revealing the correlation between real-space structure and chiral magnetic order at the atomic scale
2017
We image simultaneously the geometric, the electronic, and the magnetic structures of a buckled iron bilayer film that exhibits chiral magnetic order. We achieve this by combining spin-polarized scanning tunneling microscopy and magnetic exchange force microscopy (SPEX) to independently characterize the geometric as well as the electronic and magnetic structures of nonflat surfaces. This new SPEX imaging technique reveals the geometric height corrugation of the reconstruction lines resulting from strong strain relaxation in the bilayer, enabling the decomposition of the real-space from the electronic structure at the atomic level and the correlation with the resultant spin-spiral ground sta…
Optimal ferromagnetically-coated carbon nanotube tips for ultra-high resolution magnetic force microscopy
2013
Using single-walled carbon nanotubes homogeneously coated with ferromagnetic metal as ultra-high resolution magnetic force microscopy probes, we investigate the key image formation parameters and their dependence on coating thickness. The crucial step of introducing molecular beam epitaxy for deposition of the magnetic coating allows highly controlled fabrication of tips with small magnetic volume, while retaining high magnetic anisotropy and prolonged lifetime characteristics. Calculating the interaction between the tips and a magnetic sample, including hitherto neglected thermal noise effects, we show that optimal imaging is achieved for a finite, intermediate-thickness magnetic coating, …
MOVPE growth of Ga 3D structures for fabrication of GaN materials
2004
Abstract This paper presents the growth and characterization of metallic gallium three-dimensional (3D) structures and preliminary results of their transformation into GaN-like structures. The structures were grown by metal-organic vapour phase epitaxy (MOVPE), using trimethyl gallium as gallium precursor on silicon (1 0 0). The growth temperature was between 550°C and 750°C. Interesting and new metallic structures were obtained with our growth parameters: balloon (montgolfier-like structure) and cauliflower-like. These metallic structures can grow up perpendicular to the substrate surface and have diameters between 0.1 and 5 μm, depending on the growth conditions. Moreover, selective metal…
Characterizing low-coordinated atoms at the periphery of MgO-supported Au islands using scanning tunneling microscopy and electronic structure calcul…
2010
The perimeter of oxide-supported metal particles is suggested to be of pivotal importance for various catalytic processes. To elucidate the underlying effects, the electronic properties of edge and corner atoms of planar Au clusters on MgO/Ag(001) thin films have been analyzed with scanning tunneling microscopy and electronic structure calculations. The low-coordinated perimeter atoms are characterized by a high density of $s$-derived states at the Fermi level. Those states accommodate transfer electrons from the MgO/Ag substrate, which render the perimeter atoms negatively charged. In contrast, the inner atoms of the island are not affected by the charge transfer and remain neutral. This c…
High-resolution mapping of the optical near-field components at a triangular nano-aperture.
2009
A triangular nano-aperture in an aluminum film was used as a probe in a scanning near-field optical microscope (SNOM) to image single fluorescent molecules with an optical resolution down to 30 nm. The differently oriented molecules were employed as point detectors to map the vectorial components of the electric field distribution at the illuminated triangular aperture. The good agreement of the experimental results with numerical simulations enabled us to determine both the field map at a triangular aperture and the exact orientations of the probing molecules.
Subwavelength imaging of field confinement in a waveguide-integrated photonic crystal cavity
2005
A photonic crystal microcavity is designed to obtain an original field distribution inside the cavity and the structure is etched inside a silicon-on-insulator waveguide. Spectral location of the photonic band gap and cavity resonance are identified by using transmittance measurements and by analyzing the light collected by a scanning near-field optical microscope probe exactly positioned on the center of the cavity. The results obtained with the two techniques are in very good agreement. Then the near-field distribution above the device is mapped and light confinement inside the cavity is evidenced. Moreover, this confined light presents some remarkable patterns which clearly correspond to…
Comparative evaluation of sealing ability, penetration and adaptation of a self etching pit and fissure sealant- stereomicroscopic and scanning elect…
2019
Background The efficacy of pit and fissure sealants in preventing occlusal caries is a well-established fact. Considering the difficulty in achieving strict isolation for a longer duration while treating the pediatric patients, a simplified procedure of sealant application is desirable. While, a self-etching sealant, Prevent Seal offers a quick procedure, the physical properties of this material haven’t been studied yet. Thus, this study was aimed to comparatively evaluate sealing ability, penetration and adaptation of a self-etching pit and fissure sealant and a conventional resin sealant. Material and Methods This was an in vitrointergroup comparative study, which consisted of 2 groups- G…
Simultaneous detection of tissue autofluorescence decay distribution and time-gated photo-bleaching rates
2015
ABSTRACT Experimental methodology for parallel measurements of in-vivo skin autofluorescence (AF) lifetimes and photo-bleaching dynamic has been developed and tested. The AF lifetime decay distributio ns were periodically collected from fixed tissue area with subsequent detection of the fluorescence intensity decrease dynamic at different time gates after the pulse excitation. Temporal distributions of human in-vivo skin AF lifetimes and bleaching kinetics were collected and analyzed by means of commercial time-corr elated single photon counting system. Keywords: TCSPC, skin autofluoresc ence, and photo-bleaching. 1. INTRODUCTION Laser induced time-resolved autofluorescence (AF) spectroscop…
A quantitative electron-microscopic study of a linear polyethylene fraction crystallized at different temperatures
1981
Replica and thin-section electron microscopy was performed on a linear polyethylene fraction (Mw = 1.89 × 105, Mn = 1.79 × 10 5) which was either isothermally crystallized or quenched at difference temperatures. The results are numerically analyzed in such a manner so as to give the distribution of the total long spacing and of the crystallite and amorphous thicknesses. The quantitative information about the maximum and minimum values for these parameters at each crystallization temperature yields important clues as to possible molecular processes involved. Qualitative information regarding general morphology, molecular tilt with respect to the lamellar surface, and possible crystallographi…
The effect of oxalate-based desensitizers on the microleakage and shear bond strength of resin modified glass ionomer
2017
Background The first line of intervention to alleviate tooth sensitivity is to use dentin desensitizers such as oxalate-based desensitizers. When the dentin sensitivity continues even after application of desensitizers the next intervention would be restoration of the lesion. The aim of this in vitro study was to investigate the effect of prior application of oxalate-based desensitizer on the marginal microleakage and shear bond strength of resin modified glass ionomer (RMGI) restorations. Material and methods In order to prepare the specimens for microleakage test standard class v cavities were prepared on buccal surfaces of 45 teeth. The specimens were randomly divided into three equal gr…