Search results for "Paramagnetic"

EPR DOSIMETRY INTERCOMPARISON USING SMART PHONE TOUCH SCREEN

2014

This paper presents the results of an interlaboratory comparison of retrospective dosimetry using the electron paramagnetic resonance method. The test material used in this exercise was glass coming from the touch screens of smart phones that might be used as fortuitous dosimeters in a large-scale radiological incident.

DATING OF BRAZILIAN SHELLS THROUGH ELECTRON PARAMAGNETIC RESONANCE

2020

Chapter 8: EPR in glass ceramics

2019

The development of novel materials requires a profound understanding of the relationship between a material's performance and its structural properties. Electron paramagnetic resonance (EPR) is a well-established technique for a direct detection and identification of paramagnetic defects in solids. This chapter provides an overview of the applicability of continuous wave EPR spectroscopy in the studies of glass ceramics focusing on transition metal (Mn2 +, Cu2 +, Cr3 +) and rare earth (Gd3 +, Eu2 +, Er3 +, Yb3 +) ion local structure analysis. EPR spectra features of the above-mentioned paramagnetic probes in glasses and glass ceramics are compared and discussed in detail. The chapter also s…

The VN2 negatively charged defect in diamond. A quantum mechanical investigation of the EPR response

2020

Abstract The VN 2 − defect in diamond consists of a vacancy surrounded by two substitutional nitrogen atoms, which lower the local symmetry from Td to C2v. Calculations of the doublet ground state geometry, electronic structure, EPR parameters, and IR spectra of this defect are reported along with a preliminary investigation of the observed optical transition. For the most part our results were obtained using a uniform charge compensated supercell approach together with the B3LYP functional and all-electron Gaussian basis sets designed for the properties studied. In particular, the computed hyperfine and quadrupolar EPR parameters for the carbon and nitrogen atoms adjacent to the vacancy ag…

Optical and electron paramagnetic resonance studies on radiation defects in Mn‐activated RbCdF 3

2007

The photoluminescence of Mn-activated RbCdF3 shows a Mn2+ emission band at 560 nm; the corresponding excitation bands are between 240 and 520 nm. After X-irradiation an increased Mn2+ emission can be observed and the excitation spectrum shows an additional broad intense band at 300 nm. Upon excitation at 300 nm the intensity of the Mn2+ emission decreases, whereas excitation at 240 nm leads to an increase in the PL intensity. Electron paramagnetic resonance shows that the number of Mn2+ ions is reduced upon X-irradiation; the original Mn2+ level can be restored upon optical bleaching. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Optical and magneto‐optical studies of Mn‐activated LiBaF 3

2005

The photoluminescence (PL) of Mn-doped LiBaF3 shows a weak Mn2+ emission band at 710 nm; the corresponding excitation bands are between 210 and 620 nm. After X-irradiation the PL spectrum shows two new bands peaking at 600 and 670 nm that are tentatively assigned to perturbed Mn2+ emissions; the intensity of all PL bands is increased. Magnetic circular dichroism (MCD) and the MCD-detected electron paramagnetic resonance (EPR) measurements show that F-type centres are formed after X-irradiation. The EPR measurements indicate that there is a spatial correlation between the F-type centre and the Mn2+ dopant. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Simple Circuit Models for Studying Global Earthing Systems

2007

The paper proposes three simple circuit models for the simulation of the behaviour of a global earthing system during different fault events. The models allow one the evaluation of the maximum earth potential rise at every possible fault location and for every possible fault event. The three considered fault events are: single-line-to-earth fault inside a MV/LV substation, double-earth-fault in a MV line, single-line-to-earth fault inside a HV/MV station. After having illustrated the hypotheses at the basis of the study, the circuit models for the three fault events are presented and a numerical example shows how to use them in order to check the "global safety" of the interconnected earthi…

Ligand-Binding Cooperativity Effects in Polymer-Protein Conjugation.

2019

We present an electron paramagnetic resonance (EPR) spectroscopic characterization of structural and dynamic effects that stem from post-translational modifications of bovine serum albumin (BSA), an established model system for polymer-protein conjugation. Beyond the typical drug delivery and biocompatibility aspect of such systems, we illustrate the causes that alter internal dynamics and therefore functionality in terms of ligand-binding to the BSA protein core. Uptake of the paramagnetic fatty acid derivative 16-doxyl stearic acid by several BSA-based squaric acid macroinitiators and polymer-protein conjugates was studied by EPR spectroscopy, aided by dynamic light scattering (DLS) and z…

Interaction of half-sandwich alkylmolybdenum(III) complexes with B(C6F5)3. The X-ray structure of [CpMo(η4-C4H6)(μ-Cl)(μ-CH2)(O)MoCp][CH3B(C6F5)3]

2001

Abstract The reactions of the half-sandwich molybdenum(III) complexes CpMo(η 4 -C 4 H 4 R 2 )(CH 3 ) 2 , where Cpη 5 -C 5 H 5 and RH or CH 3 , with equimolar amounts of B(C 6 F 5 ) 3 have been investigated in toluene. EPR monitoring shows the formation of an addition product which does not readily react with Lewis bases such as ethylene, pyridine, or PMe 3 . The analysis of the EPR properties and the X-ray structure of a decomposition product obtained from dichloromethane, [CpMo(η 4 -C 4 H 6 )(μ-Cl)(μ-CH 2 )(O)MoCp][CH 3 B(C 6 F 5 ) 3 ], indicate that the borane attack has occurred at the methyl position.

Crucial dependence of excimer laser toughness of “wet” silica on excess oxygen

2011

Creation of point defects by ArF (6.4 eV) and F2 laser (7.9 eV) irradiation in synthetic “wet” silica glass thermally loaded with interstitial O2 molecules was studied by optical absorption, electron paramagnetic resonance and infrared absorption. The presence of excess oxygen caused a significant increase of laser-induced ultraviolet (UV) absorption, which was 4 times (7.9 eV-irradiation) and > 20 times stronger (ArF irradiation) as compared to O2-free samples. The spectral shape of photoinduced absorption nearly completely coincided with the spectral shape of oxygen dangling bonds (NBOHC) in 3 to 6.5 eV regions. The contribution of Si dangling bonds (E' centers) was less than few % and wa…