Search results for "Microscopy"
showing 10 items of 3390 documents
Investigation of electron transfer between single plasmon and graphene by dark field spectroscopy
2020
Abstract We investigated the electron transfer time between single plasmonic gold nanoparticles and graphene with our home-build spectral imaging dark-field microscope. The process of electron transfer is supposed to be shuttling of hot electrons on the nanoparticle-graphene interface, resulting in a slight broadening of the scattering spectrum. For detecting the minor spectrum broadening, we firstly characterized our setup systematically and then calibrated its intrinsic error. We found the mechanism of a common but normally neglected setup error, scattering spectrum broadening, which is caused by the bandwidth of the incident light and could exist in most fast dark-field microscopy setups…
Evidence of hexagonal WO3 structure stabilization on mica substrate
2009
International audience; WO3 nanorods are grown by a simple vapor deposition method on a mica substrate and characterized by Selected Area Electron Diffraction and Energy Dispersive X-rays Spectroscopy. Experimental results show the clear evidence of an unexpected WO3 hexagonal structure as well as an epitaxial growth on the mica substrate. Besides, potassium is evidenced inside the nanorods. It is thus deduced that a metastable WO3 hexagonal phase is stabilized by epitaxy through a tungsten bronze interlayer having same hexagonal structure.
Atomic-resolution imaging of clean and hydrogen-terminated C(100)-(2×1)diamond surfaces using noncontact AFM
2010
Received 22 April 2010; published 14 May 2010High-purity, type IIa diamond is investigated by noncontact atomic force microscopy NC-AFM .Wepresent atomic-resolution images of both the electrically conducting hydrogen-terminated C 100 - 2 1 :Hsurface and the insulating C 100 - 2 1 surface. For the hydrogen-terminated surface, a nearly square unitcell is imaged. In contrast to previous scanning tunneling microscopy experiments, NC-AFM imaging allowsboth hydrogen atoms within the unit cell to be resolved individually, indicating a symmetric dimer alignment.Upon removing the surface hydrogen, the diamond sample becomes insulating. We present atomic-resolutionimages, revealing individual C-C dim…
Effect of Hydrogen and Absence of Passive Layer on Corrosive Properties of Aluminum Alloys
2020
This paper reports the results of research on the effect of hydrogen permeation and the absence of passive layers on the variations in the corrosive properties of aluminum alloys. The study demonstrated that such variations contribute to the deterioration of corrosive properties, which in turn contributes to shortening the reliability time associated with the operation of aluminum alloy structures. The analysis involved structural aluminum alloys: EN AW-1050A, EN AW-5754, and EN AW-6060. It was demonstrated that the absorption of hydrogen by the analyzed alloys led to the shift of the electrode potential to the negative side. The built hydrogen corrosion cells demonstrate in each case the f…
Substrate templating upon self-assembly of hydrogen-bonded molecular networks on an insulating surface.
2012
M olecular self-assembly on insulating surfaces, despite being highly relvant to many applications, generally suffers from the weak molecule–surface interactions present on dielectric surfaces, especially when benchmarked against metallic substrates. Therefore, to fully exploit the potential of molecular self-assembly, increasing the infl uence of the substrate constitutes an essential prerequisite. Upon deposition of terephthalic acid and trimesic acid onto the natural cleavage plane of calcite, extended hydrogen-bonded networks are formed, which wet the substrate. The observed structural complexity matches the variety realized on metal surfaces. A detailed analysis of the molecular struct…
Optical and morphological properties of infrared emitting functionalized silica nanoparticles
2013
Abstract The loading process of functionalized silica nanoparticles was investigated in order to obtain nanoparticles having functional groups on their surface and Near-Infrared (NIR) emission properties. The NIR emission induced by O 2 loading was studied in silica nanoparticles, produced by pyrogenic and microemulsion methods, with size ranging from 20 to 120 nm. Loading was carried out by thermal treatments in O 2 atmosphere up to 400 °C and 90 bar. The effects of the thermal treatments on the NIR emission and on the structural properties were studied by luminescence and Raman techniques, whereas the morphological features were investigated by Transmission Electron Microscopy and Atomic …
Interdependence of structural and electrical properties in tantalum/tantalum oxide multilayers
2013
International audience; Dc reactive sputtering was used to deposit tantalum metal/oxide periodic nanometric multilayers using the innovative technique namely, the reactive gas pulsing process (RGPP). Different pulsing periods were used for each deposition to produce metal-oxide periodic alternations included between 5 and 80 nm. Structure, crystallinity and chemical composition of these films were systematically investigated by Transmission Electron Microscopy (TEM) and Energy-dispersive X-ray (EDX) spectroscopy techniques. Moreover, electrical properties were also studied by the Van der Pauw technique.
Advanced time-stamped total data acquisition control front-end for MeV ion beam microscopy and proton beam writing
2013
Many ion-matter interactions exhibit [email protected] time dependences such as, fluorophore emission quenching and ion beam induced charge (IBIC). Conventional event-mode MeV ion microbeam data acquisition systems discard the time information. Here we describe a fast time-stamping data acquisition front-end based on the concurrent processing capabilities of a Field Programmable Gate Array (FPGA). The system is intended for MeV ion microscopy and MeV ion beam lithography. The speed of the system (>240,000 events s^-^1 for four analogue to digital converters (ADC)) is limited by the ADC throughput and data handling speed of the host computer.
How the formation of interfacial charge causes hysteresis in perovskite solar cells
2018
In this study, we discuss the underlying mechanism of the current-voltage hysteresis in a hybrid lead-halide perovskite solar cell. We have developed a method based on Kelvin probe force microscopy that enables mapping charge redistribution in an operating device upon a voltage- or light pulse with sub-millisecond resolution. We observed the formation of a localized interfacial charge at the anode interface, which screened most of the electric field in the cell. The formation of this charge happened within 10 ms after applying a forward voltage to the device. After switching off the forward voltage, however, these interfacial charges were stable for over 500 ms and created a reverse electri…
Electronic structure of MgO-supported Au clusters: quantum dots probed by scanning tunneling microscopy.
2007
We investigate via density functional theory (DFT) the appearance of small MgO-supported gold clusters with 8 to 20 atoms in a scanning tunneling microscope (STM) experiment. Comparison of simulations of ultrathin films on a metal support with a bulk MgO leads to similar results for the cluster properties relevant for STM. Simulated STM pictures show the delocalized states of the cluster rather than the atomic structure. This finding is due to the presence of s- derived delocalized states of the cluster near the Fermi energy. The properties of theses states can be understood from a jellium model for monovalent gold.