New Phosphorus Oxygen Hole Center in Γ-Irradiated SiO2:P2O5 Optical Fiber

1985 ◽  
Vol 61 ◽  
Author(s):  
H. Kawazoe ◽  
M. Kohketsu ◽  
Y. Watanabe ◽  
K. Shibuya ◽  
K. Muta
Keyword(s):  
Optical Absorption ◽  
Optical Fiber ◽  
Room Temperature ◽  
Hole Center ◽  
Paramagnetic Centers ◽  
Γ Irradiation ◽  
Electron Center ◽  
Oxygen Hole ◽  
New Type ◽  
Hole Centers

ABSTRACTThe formation of paramagnetic centers upon γ-irradiation was examined for the silica based waveguides doped with P2O5 by using ESR and optical absorption. The centers inherent in SiO2 glasses such as Si-E′ and OHC were found to be replaced with P-related centers such as phosphorus oxygen hole centers and phosphorus electron center by introducing a small amount of P2O5. New type of POHC was detected especially in the glass with [P2O5] of 1.3 mol % at 77K, which was assumed to be a precursor of the POHC stable at room temperature. The correlation between γ-induced loss-increase and the formation of these defects was examined.

Copper-associated aluminum ionized center [AlO4−/Cu++]+ in a γ-irradiated copper (I)-containing silica glass

2000 ◽  
Vol 15 (3) ◽  
pp. 824-831 ◽  
Author(s):  
Radhaballabh Debnath
Keyword(s):  
Oxygen Atom ◽  
Silica Glass ◽  
Room Temperature ◽  
Copper Ion ◽  
Monovalent Cation ◽  
Hole Center ◽  
Γ Irradiation ◽  
New Type ◽  
Cuprous Ion ◽  
Hole Centers

A new type of aluminum ionized center associated with the copper ion [AlO4−/Cu++]+ has been observed in a copper(I)-containing silica glass upon γ-irradiation at room temperature. The center, unlike many other previously reported monovalent cation-compensated aluminum ionized hole centers [AlO4/M+]+, where M+ = H+, Li+, Na+, Ag+, etc., behaves more like a simple ionized center rather than an ionized hole center. We argue that complete compensation of the hole on the aluminum ion of the center becomes possible because of the compensating copper ion. This is accomplished by the donation of an electron by the cuprous ion to the neighboring irradiationgenerated [AlO4]0 hole via that oxygen atom of the (AlO4), which is nearest to the cation.

The Effect of Electron Irradiation on the Structure of Sodium Aluminum-Iron Phosphate Glasses

MRS Advances ◽  
2016 ◽  
Vol 1 (63-64) ◽  
pp. 4227-4232 ◽  
Author(s):  
S.V. Stefanovsky ◽  
O.I. Stefanovsky ◽  
M.I Kadyko ◽  
V.A. Zhachkin ◽  
L.D. Bogomolova
Keyword(s):  
Room Temperature ◽  
Structural Evolution ◽  
Iron Phosphate ◽  
Esr Spectra ◽  
Phosphate Glasses ◽  
Water Molecules ◽  
Oxygen Hole ◽  
Bending Modes ◽  
Iron Phosphate Glasses ◽  
Hole Centers

ABSTRACTGlasses of the series (mol.%) 40 Na2O, (20-x) Al2O3, x Fe2O3, 40 P2O5 were irradiated with 8 MeV electrons to doses equivalent of 0.1, 0.5, and 1.0 MGy and characterized by FTIR spectroscopy and ESR at room temperature. FTIR spectra of all the glasses consist of strong bands due to O-P-O stretching modes in (PO4)3- and (P2O7)4- units at 1000-1200 cm-1, P-O-P stretching modes at 900-950 cm-1 (νas) and 700-750 cm-1 (νs), and bending modes in the PO4 units. The wavenumber range lower 800 cm-1 has some contribution due to stretching modes in MO4 and MO6 (M = Al, Fe) units. Moreover the bands at 3300-3700 cm-1 and 1550-1650 cm-1 due to stretching and bending modes in both absorbed and structurally bound H2O molecules were present. As irradiation dose increases the bands due to stretching and bending modes in water molecules and M-O-H bonds become stronger and are split. No essential changes with increasing dose were observed within the spectral range of stretching modes of the O-P-O and P-O-P bonds. Irradiation yields phosphorus-oxygen hole centers - PO42- (D5) and PO42- (D6), and PO32- ion-radicals (D2) observable in ESR spectra of low-Fe glasses. At x>5 their responses are overlapped with strong broad line due to Fe(III). On the whole, with the increase in iron content the glass structural evolution decrease.

Thermally reversible γ-ray-induced redox reaction between substitutional iron and aluminum impurity centers in a silica glass

2001 ◽  
Vol 16 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Radhaballabh Debnath
Keyword(s):  
Silica Glass ◽  
Γ Irradiation ◽  
Paramagnetic Resonance ◽  
Hole Trapping ◽  
Oxygen Hole ◽  
Before And After ◽  
Impurity Centers ◽  
Spin Resonances ◽  
Electron Paramagnetic ◽  
Hole Centers

The magnetic properties of the substitutional iron and aluminum impurity centers in a sintered Vycor silica glass were studied before and after 1.1–1.3 MeV γ irradiation. Observation of two overlapping spin resonances (g ∼ 4.20–4.28) in the spectra of both the irradiated and preirradiated glasses indicated the existence of two types of tetra coordinated substitutional iron centers of the [FeO4−/Na+]0 type. The intensity of these electron-paramagnetic resonance (EPR) signals decreased upon g irradiation of the glass with concomitant generation of aluminum hole center [AlO4]0, which was manifested by the occurrence of a new six-line EPR signal with g 4 2.009, while thermal annealing of these aluminum oxygen hole centers restores the intensity of the iron centers almost to their preirradiation level. This result suggests that if not the whole, a major fraction of the electrons released in the process of g-ray-induced hole trapping at the Al site are captured by the substitutional iron centers. The electron traps, thus formed, are quite stable and can be deactivated by thermal stimulation.

The Observations of Paramagnetic Centers in Tellurite Glasses

1994 ◽  
Vol 373 ◽  
Author(s):  
J.D. Prohaska ◽  
J. Li ◽  
S. Kannan ◽  
E. Snitzer ◽  
J.S. Wang ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Room Temperature ◽  
The Other ◽  
Tellurite Glasses ◽  
Hole Center ◽  
Paramagnetic Centers ◽  
First Report ◽  
Esr Spectrum ◽  
Radiation Induced

AbstractThis is the first report of ESR observations of three distinct paramagnetic centers in TeO29 glasses. One center is intrinsic to the glass and the other two are induced by KrFexcimer-laser radiation. The intrinsic center with a broad ESR spectrum is tentatively identified as an oxygen-associated hole center. One radiation-induced center fades slowly at room temperature; its proposed structure is that of an electron trapped in a diffuse orbital associated with a modifier ion. The other radiation-induced center is stable at room temperature and corresponds to the Vo· center observed in crystalline paratellurite.

Measurement of Optical Absorption in Very Thin Low-Loss SiO2 Films

1987 ◽  
Vol 105 ◽  
Author(s):  
Robert M. Curran ◽  
Thomas M. Crook ◽  
J. David Zook
Keyword(s):  
Thin Films ◽  
Optical Absorption ◽  
Optical Fibers ◽  
Resonant Cavity ◽  
Plasma Radiation ◽  
Low Loss ◽  
Plasma Irradiation ◽  
Oxygen Hole ◽  
Low Levels ◽  
Hole Centers

AbstractWhile low levels of optical absorption are easily measured in SiO2 bulk samples or optical fibers, we present here a method of detirmining low levels of absorption in thin films of SiO2. Films are deposited on top of high reflectivity multi-layer miriors, and absorption is derived from the time decay in a resonant cavity of threj mirrorsgt 633 nm. Absorption coefficients on the order of 1 cm−1. (k = 10−5) can be measured in films as thin as 100 Angstroms.With this method, we find that absorption at 633 nm can be induced in SiO2 films by exposing them to a He-Ne plasma discharge. Although the plasma radiation (>10 eV) is absorbed near the SiO2 surface, the plasma-induced absorption is uniform within the SiO2 film. This was shown by plasma irradiation of SiO2 films of 4arying thickness, together with computer calgulation of the optical properties of multilayer thin films. Similar absorption behavior has been reported in SiO2 optical fibers and may be due here to DIA (Drawing-Induced Aisorption) centers or NBOHCs (Non-Bridging Oxygen Hole Centers).

Generation ofE’ centers and oxygen hole centers in synthetic silica glasses by γ irradiation

1993 ◽  
Vol 48 (5) ◽  
pp. 3116-3123 ◽  
Author(s):  
H. Imai ◽  
K. Arai ◽  
J. Isoya ◽  
H. Hosono ◽  
Y. Abe ◽  
...  
Keyword(s):  
Γ Irradiation ◽  
Silica Glasses ◽  
Oxygen Hole ◽  
Hole Centers

Vacuum ultraviolet optical absorption band of non-bridging oxygen hole centers in SiO2 glass

2002 ◽  
Vol 122 (3-4) ◽  
pp. 117-120 ◽  
Author(s):  
Hideo Hosono ◽  
Koichi Kajihara ◽  
Takenobu Suzuki ◽  
Yoshiaki Ikuta ◽  
Linards Skuja ◽  
...  
Keyword(s):  
Absorption Band ◽  
Optical Absorption ◽  
Vacuum Ultraviolet ◽  
Sio2 Glass ◽  
Optical Absorption Band ◽  
Oxygen Hole ◽  
Hole Centers

Electron Paramagnetic Resonance of Organic and Inorganic Centers in γ-Irradiated Natural Sepiolite Minerals

2006 ◽  
Vol 61 (7-8) ◽  
pp. 413-417 ◽  
Author(s):  
Rahmi Köseoğlua ◽  
Fevzi Köksalb ◽  
Mehmet Akkurt ◽  
Emin Çiftçi
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Microwave Power ◽  
Room Temperature ◽  
Paramagnetic Centers ◽  
Γ Irradiation ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

Natural sepiolite minerals and their γ -irradiated forms were investigated by electron paramagnetic resonance (EPR) at room temperature and at 113 K. The EPR signals in powders of natural sepiolite were observed due to clusters of Fe3+ ions. The paramagnetic centers produced by γ - irradiation of natural sepiolite minerals were attributed to the ĊH3 at room temperature and ṠO−2 and ṠO−3 radicals at 113 K. These centers were found to be perfectly observable above 20 mW microwave power. The g values of all paramagnetic centers have been measured and the A values of some of them have been reported. The results were consistent with the literature data for similar paramagnetic centers.

A Firmly Localized Hole Center in the Mineral Brazilianite NaAl3(PO4)2(OH)4

1982 ◽  
Vol 37 (3) ◽  
pp. 280-286 ◽  
Author(s):  
A. Requardt ◽  
F. Hill ◽  
G. Lehmann
Keyword(s):  
Room Temperature ◽  
Lone Pair ◽  
Hole Center ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Oxygen Ions ◽  
Large Distortion ◽  
Oxygen Lone Pair ◽  
Impurity Ion ◽  
Hole Centers

Abstract A hole center on an oxygen adjacent to one aluminum and one phosphorous was detected and analyzed in natural and X-ray irradiated brazilianite. The slightly anisotropic 27 Al shfs splitting is larger than in many other hole centers in which the Al is a lower valency impurity ion with only a coordinative bond to an oxygen lone pair. The hole is trapped at an oxygen with particularly long bond distances to one P and two Al. Thus one structural Al must be substituted by a presumably divalent cation of yet unknown nature. No optical absorption is associated with this center, therefore the large distortion of the coordination polyhedra must be responsible for absence of a light-induced hole transfer between different oxygen ions. Comparison with other systems suggests that the energy differences for other configurations of the hole center are also too high to allow thermal hopping of the hole at or below room temperature. Possible mechanisms for formation and destruction of this center are deduced from experimental results.

Gamma and UV Radiation-Induced Color Centers in Optical Fibers

2005 ◽  
Vol 480-481 ◽  
pp. 323-328 ◽  
Author(s):  
Sylvain Girard ◽  
E. Régnier ◽  
A. Boukenter ◽  
Y. Ouerdane ◽  
J.-P. Meunier ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Fiber Type ◽  
Low Cost ◽  
Nuclear Space ◽  
Paramagnetic Centers ◽  
Oxygen Hole ◽  
Spin Resonance ◽  
Radiation Induced ◽  
Phosphorus Doped ◽  
Hole Centers

Radiation-induced losses and paramagnetic centers were investigated in phosphorusdoped and P-free multimode germanosilicate optical fibers after g-rays (~1 MeV) and ultraviolet (5 eV) exposures. After both types of irradiation, the same defects seem to be responsible of the fiber absorption in the spectral range 400 to 1650 nm. In particular, the P1 centers and the Phosphorus Oxygen Hole centers are created in both cases in the phosphorus-doped fibers and explain the high permanent radiation-induced attenuation levels observed in this fiber type. Luminescence and electron spin resonance measurements (77 K, ~9.38 GHz) on irradiated samples confirm that the GeE’, SiE’ and NBOHC defects are also generated in the different irradiated samples. From this study, it seems that the pertinence of a multimode fiber for nuclear space or civil applications could be estimated through low-cost ultraviolet measurements.

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