Radiation Damage Mechanisms In Scintillator Materials: Applications to BaF2 and CeF3

1994 ◽  
Vol 348 ◽  
Author(s):  
L. E. Halliburton ◽  
G. J. Edwards
Keyword(s):  
Low Temperature ◽  
Optical Absorption ◽  
Radiation Damage ◽  
Room Temperature ◽  
Epr Spectrum ◽  
Absorption Bands ◽  
Paramagnetic Resonance ◽  
Damage Mechanisms ◽  
Temperature Damage ◽  
F Centers

ABSTRACTResults from recent radiation damage studies in high quality BaF2 and CeF3 crystals are presented. Optical absorption and electron paramagnetic resonance (EPR) techniques are used to identify specific radiation damage mechanisms. Specific attention is given to the role of oxygen and hydrogen in the room temperature damage of BaF2. Also, Mn2+ ions are shown to change valence state in BaF2during room temperature irradiation. Numerous optical absorption bands are created in CeF3 during irradiations at low temperature. These bands are associated with electron traps (either F centers or Ce2+ ions) and they thermal anneal below room temperature. An EPR spectrum, assigned to F centers, is observed in low-temperature irradiated CeF3.

Optical and EPR Study of Defects in Cadmium Germanium Arsenide

2002 ◽  
Vol 744 ◽  
Author(s):  
Lihua Bai ◽  
N. Y. Garces ◽  
Nanying Yang ◽  
P. G. Schunemann ◽  
S. D. Setzler ◽  
...  
Keyword(s):  
Absorption Band ◽  
Optical Absorption ◽  
Room Temperature ◽  
Hole Concentration ◽  
Paramagnetic Defect ◽  
Paramagnetic Resonance ◽  
Anion Site ◽  
Shallow Acceptors ◽  
P Type ◽  
Cadmium Germanium Arsenide

ABSTRACTBulk crystals of CdGeAs2 have been characterized using photoluminescence (PL), optical absorption, Hall effect, and electron paramagnetic resonance (EPR) techniques. An absorption band near 5.5 microns at room temperature is observed in all of the p-type samples we have studied. A correlation between the magnitude of this optical absorption and the excess hole concentration at room temperature is established. Also, an EPR signal is found to correlate with the strength of this absorption band. PL data are consistent with an increased concentration of shallow acceptors being present in high-absorption samples. From the EPR data, we suggest that a model for the paramagnetic defect associated with the absorption at 5.5 microns may be an acceptor on an anion site.

Paramagnetic resonance and optical absorption of trapped holes and electrons in irradiated KCI: Ag

1963 ◽  
Vol 271 (1345) ◽  
pp. 243-267 ◽  
Keyword(s):  
Electron Spin Resonance ◽  
Low Temperature ◽  
Optical Absorption ◽  
Electron Spin ◽  
Optical Absorption Spectra ◽  
Paramagnetic Resonance ◽  
Spin Resonance ◽  
Impurity Ions ◽  
Temperature Irradiation ◽  
Positive Holes

The electron spin resonance and optical absorption spectra of crystals of KCl containing silver impurity ions were examined after the crystals had been X -irradiated at 77 °K. It is shown that the silver impurity ions act as traps for both electrons and positive holes. A description is given of the annealing behaviour of the crystals after low-temperature irradiation.

Metastable Percolation Phase Formation in Lif Implanted with Alkali Ions

1981 ◽  
Vol 7 ◽  
Author(s):  
J. Davenas ◽  
P. Thevenard ◽  
C. Dupuy
Keyword(s):  
Low Temperature ◽  
Optical Absorption ◽  
Phase Formation ◽  
Room Temperature ◽  
Critical Concentration ◽  
External Perturbation ◽  
Metallic Layer ◽  
Alkali Ions ◽  
Conducting State ◽  
Equilibrium Situation

ABSTRACTThe formation of a continuous metallic layer in the doped region of LiF crystals implanted at low temperature, has been explained by the formation of bridges between next neighbouring alkali ions of the lattice around-each implanted ion. For a critical concentration of implanted ions it is possible to show using statistical arguments that conducting chains are formed by the union of these links, according to a percolation mechanism. We show that the assumption of a distribution of isolated implanted ions at low temperature is justified by the observation of their precipitation when the crystal is warmed up to room temperature. The transformation of the metallic optical absorption into the colloidal band associated with precipitates of implanted ions is correlated with the transition from a conducting state to an insulating state of the implanted layer. We show that this evolution towards an equilibrium situation may be reversed by a reirradiation, which is used as an external perturbation and that the conducting state associated with dispersed implanted ions is then once again obtained.

EPR of Gamma-irradiated L-Glutamine Hydrochloride and N-Carbamoyl-L-glutamic Acid

2005 ◽  
Vol 60 (7) ◽  
pp. 549-553 ◽  
Author(s):  
Şemsettin Osmanoğlua ◽  
Murat Aydın ◽  
M. Halim Başkana
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Glutamic Acid ◽  
Radiation Damage ◽  
Single Crystals ◽  
Room Temperature ◽  
Paramagnetic Resonance ◽  
Temperature Radiation ◽  
Gamma Irradiated ◽  
Electron Paramagnetic

The electron paramagnetic resonance spectra of γ -irradiated L-glutamine hydrochloride and N-carbamoyl- L-glutamic acid single crystals have been investigated at room temperature. Radiation damage centres are attributed to ĊH, ṄH2 and CH2Ċ(NH2)COOH radicals.

scholarly journals Temperature study of magnetic resonance spectra of co-modified (Co,N)-TiO2 nanocomposites

2016 ◽  
Vol 34 (2) ◽  
pp. 242-250 ◽  
Author(s):  
Nikos Guskos ◽  
Janusz Typek ◽  
Grzegorz Zolnierkiewicz ◽  
Aleksander Guskos ◽  
Pawel Berczynski ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Low Temperature ◽  
Cobalt Nanoparticles ◽  
Resonance Spectroscopy ◽  
Temperature Analysis ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Magnetic Polarons ◽  
Integrated Intensity ◽  
Electron Paramagnetic

AbstractThe (nCo,N)-TiO2 (n = 1, 5 and 10 wt.% of Co) nanocomposites were investigated by magnetic resonance spectroscopy in 4 K to 290 K range. Analyses of ferromagnetic/electron paramagnetic resonance (FMR/EPR) spectra in terms of four Callen lineshape components revealed the existence of two types of magnetic centers, one derived from metallic cobalt nanoparticles in superparamagnetic (SPM) phase and the other from cobalt clusters in the TiO2 lattice. Additionally, at low temperature the EPR spectrum arising from Ti3+ ions was also registered. Both relaxations of the Landau-Lifshitz type and the Bloch-Bloembergen type played an important role at high temperature in determining the linewidths and the latter relaxation was prevailing at low temperature. Analysis of the integrated intensity showed that the SPM signal is due to small size FM cobalt nanoparticles while the paramagnetic signal from Co clusters originates from those nanoparticles in which the concentration of magnetic polarons is below the percolation threshold.

scholarly journals Epr Spectrum Angular Dependences In Liyf4 Crystal / Epr Spektru Leņķiskās Atkarības Liyf4 Kristālā

2012 ◽  
Vol 49 (6-I) ◽  
pp. 49-54
Author(s):  
A. Antuzevics ◽  
A. Fedotovs ◽  
U. Rogulis
Keyword(s):  
Room Temperature ◽  
Temperature Analysis ◽  
Epr Spectrum ◽  
Spectral Parameters ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Crystal Growth Process ◽  
Before And After ◽  
Impurity Ion ◽  
Electron Paramagnetic

Abstract Electron paramagnetic resonance (EPR) measurements have been made for two perpendicular planes in a LiYF4 crystal before and after x-ray irradiation at room temperature. Analysis of the EPR spectrum angular dependence shows the presence of two defects - an impurity ion, which was embedded during the crystal growth process, and an x-ray induced defect with the g-factor of approx. 2.0. Spectral parameters and possible defect models are discussed.

EPR Studies of Mn2+-Doped Diammonium Hexaaqua Magnesium(II) Sulfate

2006 ◽  
Vol 61 (12) ◽  
pp. 683-687 ◽  
Author(s):  
Ram Kripal ◽  
Ashutosh Kumar Shukla
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Fine Structure ◽  
Single Crystals ◽  
Room Temperature ◽  
Spin Hamiltonian ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

Electron paramagnetic resonance (EPR) studies of Mn2+ impurity in single crystals of diammonium hexaaqua magnesium(II) sulfate have been carried out at 9.3 GHz (X-band) at room temperature. The EPR spectra exhibit a group of five fine structure transitions. The spin-Hamiltonian parameters were determined. Mn2+ enters the lattice interstitially. The EPR spectrum of a powder sample supports the data obtained by single crystal studies. - PACS number: 76.30

Optical Absorption Spectra of KBr:Pb2+ Crystals

1973 ◽  
Vol 51 (21) ◽  
pp. 2242-2248 ◽  
Author(s):  
Robert E. Chaney ◽  
P. W. M. Jacobs ◽  
Taiju Tsuboi
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Alkali Halide ◽  
Room Temperature ◽  
Nonlinear Least Squares ◽  
Energy Separation ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Fundamental Properties ◽  
Alkali Halide Crystals

The fundamental properties of the absorption spectra of KBr:Pb2+ crystals have been studied at various temperatures from the liquid helium range to room temperature. The observed absorption bands are assigned to the so-called A, B, C, and D' bands by analogy with the absorption bands of other s2-configuration ions in alkali halide crystals. The B, C, and D′ bands overlap but have been resolved into their components by nonlinear least squares analysis. A discussion is given of the energy separation between the B and C bands in Sn2+-, Tl+-, and Pb2+-doped alkali halide crystals.

Electron Paramagnetic Resonance and Optical Absorption Spectra of VO2+ in CsCl Single Crystals

1985 ◽  
Vol 40 (5) ◽  
pp. 511-515 ◽  
Author(s):  
G. Elbers ◽  
G. Lehmann
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Room Temperature ◽  
Ligand Field ◽  
Optical Absorption Spectra ◽  
Paramagnetic Resonance ◽  
Rapid Rotation ◽  
Vanadyl Ion ◽  
Vibrational Progression ◽  
Electron Paramagnetic

In vanadium-doped CsCl crystals grown from aqueous solutions anisotropic EPR spectra due to VO2+ are observed and analyzed at room temperature. Evidence is presented that isotropic spectra of this ion observed in this and other compounds are due to inclusions of growth solution and not to rapid rotation of the vanadyl ion in the solid as normally assumed. At 77 K a well resolved vibrational progression of about 820 cm −1 is observed in the first ligand field band of this ion. The optical absorption spectra indicate the presence of a second valence state of vanadium, most likely V3+, in varying proportions depending on the crystal growth temperature.

scholarly journals High-throughput structures of protein–ligand complexes at room temperature using serial femtosecond crystallography

IUCrJ ◽  
2019 ◽  
Vol 6 (6) ◽  
pp. 1074-1085 ◽  
Author(s):  
Tadeo Moreno-Chicano ◽  
Ali Ebrahim ◽  
Danny Axford ◽  
Martin V. Appleby ◽  
John H. Beale ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Radiation Damage ◽  
High Throughput ◽  
High Throughput Screening ◽  
Room Temperature ◽  
Data Sets ◽  
Binding Studies ◽  
X Ray ◽  
Temperature Damage ◽  
Serial Femtosecond Crystallography

High-throughput X-ray crystal structures of protein–ligand complexes are critical to pharmaceutical drug development. However, cryocooling of crystals and X-ray radiation damage may distort the observed ligand binding. Serial femtosecond crystallography (SFX) using X-ray free-electron lasers (XFELs) can produce radiation-damage-free room-temperature structures. Ligand-binding studies using SFX have received only modest attention, partly owing to limited beamtime availability and the large quantity of sample that is required per structure determination. Here, a high-throughput approach to determine room-temperature damage-free structures with excellent sample and time efficiency is demonstrated, allowing complexes to be characterized rapidly and without prohibitive sample requirements. This yields high-quality difference density maps allowing unambiguous ligand placement. Crucially, it is demonstrated that ligands similar in size or smaller than those used in fragment-based drug design may be clearly identified in data sets obtained from <1000 diffraction images. This efficiency in both sample and XFEL beamtime opens the door to true high-throughput screening of protein–ligand complexes using SFX.

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