Search results for "iTED"
showing 10 items of 2408 documents
CF3 Substitution of [Cu(P^P)(bpy)][PF6 ] Complexes: Effects on Photophysical Properties and Light-Emitting Electrochemical Cell Performance
2018
Herein, [Cu(P^P)(N^N)][PF6 ] complexes (P^P=bis[2-(diphenylphosphino)phenyl]ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos); N^N=CF3 -substituted 2,2'-bipyridines (6,6'-(CF3 )2 bpy, 6-CF3 bpy, 5,5'-(CF3 )2 bpy, 4,4'-(CF3 )2 bpy, 6,6'-Me2 -4,4'-(CF3 )2 bpy)) are reported. The effects of CF3 substitution on their structure as well as their electrochemical and photophysical properties are also presented. The HOMO-LUMO gap was tuned by the N^N ligand; the largest redshift in the metal-to-ligand charge transfer (MLCT) band was for [Cu(P^P){5,5'-(CF3 )2 bpy}][PF6 ]. In solution, the compounds are weak yellow to red emitters. The emission properties depend on the substitu…
Spatial Distribution of the Nonlinear Photoluminescence in Au Nanowires
2019
When gold nanowires are excited with a tightly focused femtosecond laser a distributed nonlinear photoluminescence (N-PL) develops throughout the entire structure. A complete spaced-resolved analysis of the spectral signature of the nanowire nonlinear response is carried out to understand the origin of the distributed nonlinear response. We discuss various mechanisms to explain the experimental data and unambiguously demonstrate that the spatial and spectral extension of the N-PL in the nanowire are mainly dictated by the propagation of a surface plasmon excited at the pump wavelength. We also present experimental signature of near-field excitation of a broadband continuum of surface plasmo…
Phase stability and oxygen-sensitive photoluminescence of ZrO2:Eu,Nb nanopowders
2018
This work was supported by institutional research funding ( IUT34-27 and IUT2-14 ) of the Estonian Ministry of Education and Research .
Generation and excitation of point defects in silica by synchrotron radiation above the absorption edge
2010
We report photoluminescence measurements carried out on amorphous SiO{sub 2} upon excitation by synchrotron light. Exposure of the as-grown material to above-edge light at low temperature induces the formation of nonbridging oxygen hole centers (NBOHC), localized in a thin layer below the surface limited by the penetration depth (tens of nm) of impinging light. After concluding the exposure to 11 eV light, stable defects are revealed by observing their characteristic 1.9 eV photoemission band excited at 4. 8eV. The local concentration of induced defects, supposedly formed by nonradiative decay of excitons, is very high (close to approx10{sup 21} cm{sup -3}) and independent of the previous h…
PBS Nanodots for Ultraviolet Radiation Nanosensor
2011
PbS nanodots embedded in a zirconium oxide nanofilm were explored as possible ultraviolet (UV) sensors for nanodosimetry purposes. The nanodots were excited by ultraviolet photons to get emission of weak electrons. The emitted charge correlated to UV exposure indicates that PbS nanodots have potential for use as UV sensors for nanodosimetry.
Near-field observation of evanescent light wave coupling in subwavelength optical waveguides
2002
International audience; We report the observation, in the range of visible frequencies, of the coupling of light into integrated waveguides of subwavelength cross-sections together with a subwavelength detection at the output, of such guides. Coupling in is produced by controlling the focusing of a laser beam totally reflected at the surface of the sample. Several tens of micrometres long dielectric ridges have been efficiently excited with this technique. The phenomenon is observed in direct space by a Photon Scanning Tunneling Microscope which also allows to test the principle of detection in a subwavelength volume.
Addressing and imaging high optical index dielectric ridges in the optical near field
2001
Experimental observation of light coupling between ${\mathrm{TiO}}_{2}$ integrated waveguides of subwavelength cross section and pure three-dimensional evanescent light fields is reported. This near-field optical phenomenon is produced by controlling the location of the focusing of a laser beam totally reflected at the surface of the sample. The phenomenon is observed in direct space with a photon scanning tunneling microscope. Dielectric ridges several tens of micrometers long have been efficiently excited with this technique. Upon excitation, the extremities of the linear dielectric wires display intense light spots localized both inside and around the ridge. For ridge lengths up to $30\e…
Theory of parabolic pulse propagation in nonlinear dispersion decreasing optical fiber amplifiers
2008
Optical fibers ; Nonlinear optics ; Optical fiber amplifiers ; Optical amplifier ; Optical solitons ; Electromagnetic wave propagation ; Pulse propagation ;; International audience; We show that pulse spectral broadening in normally dispersive nonlinear fiber amplifiers may be enhanced by introducing a suitable dispersion tapering. We obtain an analytical dispersion profile that permits one to reduce pulse propagation in a varying dispersion fiber to the case of an equivalent fiber with constant parameters.
New Schemes for the Production and Spectroscopy of Positronium
1989
The rate of positronium formation has been increased by 2–3 orders of magnitude using recently developed accelerator based slow positron sources. This opens the possibility of improvements of precision experiments on the Ps atom as well as new experiments on excited states. First evidence for enhanced metastable Ps formation is presented and future possibilities are discussed.
Ein neuartiges Verfahren der Sauerstoffdetektion für Medizin, Biologie, Umweltforschung und Biotechnik auf Basis der Lumineszenzlöschung - An Innovat…
1996
For most (aerobic) animal organisms, oxygen is a mandatory and global substrate. The accurate measurement of oxygen is therefore of importance in the fields of medicine, biology, environmental research and biotechnology. The fact that oxygen is not readily soluble in aqueous media makes its detection more difficult. In contrast to the technique of polarography, the use of luminescence quenching by paramagnetic oxygen, does not consume the oxygen. Another problem of oxygen detection in connection with respiration is the need for very short response times. A third problem, which is associated with luminescence itself, is the fading of the dyes, which results in long-term signal instability. T…