Search results for "Toe"

Mapováni spinů povrchových a bulkových Rashba stavů v tenkých vrstvách feroelektrického α-GeTe(111)

2015

Rozbíjení inverzní symetrie ve fereeleRashba efekt; Fotoemisse; DFTktrickém polovodiči způsobuje děleni stavů, tzv Rashba efekt. V tomto článku ukazujeme kompletně mapování spinové polarizace těchto Rashba stavů za pomoci spinovo rozlišené fotoemisse. The breaking of bulk inversion symmetry in ferroelectric semiconductors causes a Rashba-type spin splitting of electronic bulk bands. This is shown by a comprehensive mapping of the spin polarization of the electronic bands in ferroelectric α- GeTe(111) films using a time-of-flight momentum microscope equipped with an imaging spin filter that enables a simultaneous measurement of more than 10 000 data points. The experiment reveals an opposite…

Optoelectronic morphological image processor.

2009

A morphological optoelectronic image processor based on the threshold decomposition concept is described and demonstrated. Binary slices of a gray-scale input image are optically convolved with a binary structuring element of arbitrary size and shape in a noncoherent convolver. The slices are displayed on a liquid-crystal spatial light modulator of 320 × 264 pixels. The kernels are implemented as modifications of the system impulse response. The processor’s convolution patterns are recorded with a CCD camera and fed into a PC by a frame grabber. Subsequent elementary morphological operations are looped. Examples of processing an input image of 256 × 256 pixels and 16 gray levels with kernel…

Stabilization of polar solid oxide surfaces: competition between adsorption and reconstruction

2002

Multi-cationic spinel compounds are solids that exhibit polar faces. X-ray Photoelectron spectroscopy revealed the main phenomena allowing the stabilization of these faces, carried out as a function of the material treatment, particularly the cooling rate after thermal treatment at a high temperature (1200°C). This study showed that, whatever the cooling rate, each sample is subject to a significant hydroxylation that reduces the polarity. Nevertheless, it appears that the hydroxyl group content at the surface is a strong function of the cooling rate. Indeed, whereas quenched materials are subject to high levels of hydroxylation, slowly cooled samples are sparingly hydroxylated. This phenom…

Nonlinear polarization effects in optical fibers: polarization attraction and modulation instability [Invited]

2014

We review polarization stabilization techniques based on the polarization attraction effect in low-birefringence fibers. Polarization attraction or pulling may be based on cross-polarization modulation, on parametric amplification, and on Raman or Brillouin scattering. We also review methods for laser frequency conversion based on polarization modulation instabilities in low- and high-birefringence fibers, and photonic crystal fibers. Polarization instabilities in nonlinear fibers may also be exploited for sensing applications.

All-optical regeneration of polarization of a 40 Gbit/s return-to-zero telecommunication signal

2013

International audience; We report all-optical regeneration of the state of polarization of a 40 Gbit/s return-to-zero telecommunication signal. The device discussed here consists of a 6.2-km-long nonzero dispersion-shifted fiber, with low polarization mode dispersion, pumped from the output end by a backward propagating wave coming from either an external continuous source or a reflection of the signal. An initially scrambled signal acquires a degree of polarization close to 100% toward the polarization generator output. All-optical regeneration is confirmed by means of polarization and bit-error-rate measurements as well as real-time observation of the eye diagrams. We show that the physic…

Magneto-optical linear dichroism in threshold photoemission electron microscopy of polycrystalline Fe films.

2000

Magnetic linear dichroism in threshold photoemission has been exploited to obtain magnetic contrast in a photoemission electron microscope using a mercury arc lamp. The dichroism at threshold can be described similar to the magneto-optical Kerr effect in the region of visible light. The asymmetry of electron intensity observed for a 100 nm polycrystalline Fe film on silicon is A=(0.37+/-0.05)%. The asymmetry occurs for the geometry of the transverse Kerr effect. For unpolarized light the asymmetry was about half the value observed for linearly polarized light. Threshold photoemission microscopy has a large potential for high resolution magnetic domain imaging with fast data acquisition.

Geographical and ecological outline of metal(loid) accumulating plants in Italian vascular flora

2018

The decontamination of heavy metal polluted soils is one of the major challenges that our industrialized world has to face. Remediation technologies are being developed and employed in order to reduce the potential hazards of metal and metalloid contamination. Plants capable of uptaking metals and metalloids in their tissues can be an effective tool to remove such pollutants from contaminated soils. The use of this plant-driven process (Phytoremediation) requires the knowledge of the right phytoextractors to use when facing different types of contamination. The aim of this paper is to provide an inventory of phytoextractors that can be used in Phytoremediation procedures in Italy. The check…

Polymer electrolytes based on PAN and mixed salts for photoelectrochemical appilcations: formulation and characterization

2012

Polymeric C3N4 and O-doped C3N4: Photoelectrochemical and EPR Features for Selective Photocatalytic Oxidation of Alcohols to Aldehydes

2018

Polymeric C3N4 and O-doped C3N4: Photoelectrochemical and EPR Features for Selective Photocatalytic Oxidation of Alcohols to Aldehydes

Tunable Phosphorescent Emission through Energy Transfer within Multilayer Thin Films Based on a Carbazole-Based Host and Ir(III)-Complex Guest System

2009

A new method to tune both phosphorescence emission intensity and spectroscopic colors based on the alternatively structured host/guest multilayer thin films prepared by the spin-assisted LbL deposition is presented. Their emission characteristics are demonstrated with pairs of positively charged Ir-PEI complexes as guests and negatively charged CBZ-PAA as hosts. The phosphorescent emission of Ir-PEI complexes is enhanced by the energy transfer from the host to the guest and, additionally, this energy transfer can be finely tuned by the insertion of spacer layers between the phosphorescent donor and acceptor layers to vary the emission intensity as well as to render different emission colors.