Search results for "luminescence."
showing 10 items of 1568 documents
Radioluminescence Response of Ce-, Cu-, and Gd-Doped Silica Glasses for Dosimetry of Pulsed Electron Beams
2021
Radiation-induced emission of doped sol-gel silica glass samples was investigated under a pulsed 20-MeV electron beam. The studied samples were drawn rods doped with cerium, copper, or gadolinium ions, which were connected to multimode pure-silica core fibers to transport the induced luminescence from the irradiation area to a signal readout system. The luminescence pulses in the samples induced by the electron bunches were studied as a function of deposited dose per electron bunch. All the investigated samples were found to have a linear response in terms of luminescence as a function of electron bunch sizes between 10−5 Gy/bunch and 1.5×10−2 Gy/bunch. The presented results show that these…
Optical properties and photosensitivity of vacuum synthesized Ge-doped sol-gel amorphous SiO/sub 2/
2005
We report optical and electron paramagnetic resonance investigations of gamma ray irradiation effects in sol-gel Ge-doped amorphous SiO/sub 2/. The studied materials have Ge-doping levels up to 10/sup 4/ molar part per million and were densified by two routes differing for the atmosphere: O/sub 2/+N/sub 2/ or vacuum. The obtained results evidence that irradiation affects matrix sites inducing paramagnetic defects. Furthermore, the comparison between the two densification procedures shows that vacuum atmosphere induces higher radiation sensitivity.
Photoluminescence time decay of surface oxygen deficient centers in un‐doped and Ge‐doped silica
2005
We report a study of the emission decay from the singlet excited state of two fold coordinated Si and Ge centers stabilized on the surface of silica and Ge-doped silica. The PL lifetimes are of the order of nanoseconds and increase on decreasing the temperature. The results suggest that, for the surface centers, the phonon assisted intersystem-crossing process linking the excited states affects the decay rates, is effective down to low temperatures and is distributed because of the inhomogeneity of the defects. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition.
2013
A study of transmittance and photoluminescence spectra on the growth of oxygen-rich ultra-thin ZnO films prepared by atomic layer deposition is reported. The structural transition from an amorphous to a polycrystalline state is observed upon increasing the thickness. The unusual behavior of the energy gap with thickness reflected by optical properties is attributed to the improvement of the crystalline structure resulting from a decreasing concentration of point defects at the growth of grains. The spectra of UV and visible photoluminescence emissions correspond to transitions near the band-edge and defect-related transitions. Additional emissions were observed from band-tail states near th…
Optical and structural properties of Al 2 O 3 /ZnO nanolaminates deposited by ALD method
2014
International audience; We report on the investigation of optical and structural properties of Al2O3/ZnO nanolaminates. The nanolaminates were deposited on Si and glass substrates by Atomic layer deposition method. Structural properties of nanolaminates were studied by SEM, GIXRD, and AFM. Optical characterization was performed by transmittance and photoluminescence spectroscopy. Complex analysis of monolayer properties was done by ellipsometry. Optical constants for Al2O3 and ZnO monolayer were calculated.
Influence of PDA Coating on the Structural, Optical and Surface Properties of ZnO Nanostructures
2020
Polydopamine (PDA) is a new biocompatible material, which has prospects in biomedical and sensor applications. Due to functional groups, it can host wide range of biomolecules. ZnO nanostructures are well known templates for optical sensors and biosensors. The combination of ZnO and PDA results in a change of optical properties of ZnO&ndash
Properties of Gd-Doped Sol-Gel Silica Glass Radioluminescence under Electron Beams
2022
International audience; The radiation-induced emission (RIE) of Gd3+-doped sol–gel silica glass has been shown to have suitable properties for use in the dosimetry of beams of ionizing radiation in applications such as radiotherapy. Linear electron accelerators are commonly used as clinical radiotherapy beams, and in this paper, the RIE properties were investigated under electron irradiation. A monochromator setup was used to investigate the light properties in selected narrow wavelength regions, and a spectrometer setup was used to measure the optical emission spectra in various test configurations. The RIE output as a function of depth in acrylic was measured and compared with a reference…
Self-healing, luminescent metallogelation driven by synergistic metallophilic and fluorine–fluorine interactions
2020
Square planar platinum(ii) complexes are attractive building blocks for multifunctional soft materials due to their unique optoelectronic properties. However, for soft materials derived from synthetically simple discrete metal complexes, achieving a combination of optical properties, thermoresponsiveness and excellent mechanical properties is a major challenge. Here, we report the rapid self-recovery of luminescent metallogels derived from platinum(ii) complexes of perfluoroalkyl and alkyl derivatives of terpyridine ligands. Using single crystal X-ray diffraction studies, we show that the presence of synergistic platinum-platinum (PtMIDLINE HORIZONTAL ELLIPSISPt) metallopolymerization and f…
Non-conventional synthesis and photophysical studies of platinum(ii) complexes with methylene bridged 2,2′-dipyridylamine derivatives
2019
Methylene bridged 2,2′-dipyridylamine (dpa) derivatives and their metal complexes possess outstanding properties due to their inherent structural flexibility. Synthesis of such complexes typically involves derivatization of dpa followed by coordination on metals, and may not always be very efficient. In this work, an alternative synthetic approach, involving the derivatization step after – rather than prior to – coordination of dpa on metal center, is proposed and applied to synthesis of a number of platinum(II) complexes with substituted benzyldi(2-pyridyl)amines. Comparison with the more conventional synthetic route reveals greater efficiency and versatility of the proposed approach. The …
Effect of Er3+-doping on 65GeS2-25Ga2S3-10CsCl glass probed by annihilating positrons
2019
Abstract Effect of Er3+-doping resulting in pronounced mid-IR fluorescence functionality was examined first in chalcohalide 65GeS2-25Ga2S3-10CsCl glass using positron annihilation lifetime (PAL) spectroscopy. The detected PAL spectra were reconstructed from unconstrained x2-term analysis employing two-state simple trapping model for one kind of positron trapping free-volume defects, the parameterization being performed at the example of 65GeS2-25Ga2S3-10CsCl glass doped with 0.6 at. % of Er3+. The observed decrease in positron trapping rate was proved to be primary void-evolution process in this Er-activated glass, like in many other chalcogenide glasses affected by rare earth doping. The n…