1966
DOI: 10.1021/j100877a009
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Electron Spin Resonance Studies of γ-Irradiated High Surface Area Silica. I. Identification of Defects

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Cited by 29 publications
(7 citation statements)
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“…It is to be noted that these spectra are quite different from those obtained for irradiated Vycor glasses, for which a signal showing a hyperfine coupling with boron was predominant. [69] The g values we have obtained may correspond to oxygen-associated hole centers (OHCs) as designated by Stapelbroek et al [70,71] who distinguished the "wet" OHC for SiOC and the "dry" OHC for the peroxy radical SiOOC ( denotes three bonds of the silicon atom with oxygen atoms). The "wet" OHC, which consists of a hole trapped on a single nonbridging oxygen, [71] is also called nonbridging oxygen hole center (NBOHC, SiOC).…”
Section: Epr Measurements Of Dried and Hydrated Glassesmentioning
confidence: 92%
See 1 more Smart Citation
“…It is to be noted that these spectra are quite different from those obtained for irradiated Vycor glasses, for which a signal showing a hyperfine coupling with boron was predominant. [69] The g values we have obtained may correspond to oxygen-associated hole centers (OHCs) as designated by Stapelbroek et al [70,71] who distinguished the "wet" OHC for SiOC and the "dry" OHC for the peroxy radical SiOOC ( denotes three bonds of the silicon atom with oxygen atoms). The "wet" OHC, which consists of a hole trapped on a single nonbridging oxygen, [71] is also called nonbridging oxygen hole center (NBOHC, SiOC).…”
Section: Epr Measurements Of Dried and Hydrated Glassesmentioning
confidence: 92%
“…[74,77,78] Moreover, we did not observe E' center ( SiC) type of defects. [69,79,80] The amount of defects formed in glasses is presented in Figure 7. The measured spin concentrations at 1 MGy are all in the 10 15 -10 16 spin g À1 range.…”
Section: Epr Measurements Of Dried and Hydrated Glassesmentioning
confidence: 99%
“…On exposure of irradiated silica-alumina gel to each of 18 reagents and on irradiation in the presence of each of 12 reagents, without exception, the behavior of visible coloration parallels that of the esr signal attributed to an A1 positive-hole center. Such a correlation provides strong support for identification of the visible color centers in silica-alumina gel as A1 positivehole centers.2 Identity of positive-hole centers and centers of chemical activity for isopropylbenzene dealkylation is indicated by comparison of the limiting yield of 16 X 1017 positive-hole centers per gram with that of ^13 X 1017 benzene molecules per gram obtained in isopropylbenzene dealkylation.2 A model is proposed which describes the generality of results obtained in radiation studies with silicaalumina gel.…”
Section: Discussionmentioning
confidence: 76%
“…In this work, the silicate glass contains silicon and boron ions, both of which are prone to produce the corresponding defects after X‐ray irradiation. As shown in Figure 2A, silicon oxygen hole center (Si‐OHC, ≡Si‐O°, g∼2.009), 25 boron oxygen hole center (B‐OHC, = B‐O°, g∼2.002), 26 and silicon dangling bond (Si‐E’, ≡Si‐, g∼2.001) 27 are found in the irradiated P0 samples. Defects are formed when X‐ray photon energy is absorbed by the glass via the following processes 25–27 : SiO+h+SiOofalse(SiOHCfalse)\begin{equation} \equiv {\rm{Si - O + }}{{\rm{h}}^{\rm{ + }}} \leftrightarrow \def\eqcellsep{&}\begin{array}{@{}*{1}{c}@{}} { \equiv {\rm{Si - }}{{\rm{O}}^{\rm{o}}}}\\ {({\rm{Si - OHC}})} \end{array} \end{equation} =BO+h+=BOofalse(BOHCfalse)\begin{equation}{\rm{ = B - O + }}{{\rm{h}}^ + } \leftrightarrow \def\eqcellsep{&}\begin{array}{@{}*{1}{c}@{}} {{\rm{ = B - }}{{\rm{O}}^{\rm{o}}}}\\ {({\rm{B - OHC}})} \end{array} \end{equation} SiOSiSi·false(SinormalEfalse)+SinormalOfalse(SiOHCfalse)+e\begin{equation} \equiv {\rm{Si - O - Si}} \equiv \leftrightarrow \def\eqcellsep{&}\begin{array}{@{}*{1}{c}@{}} { \equiv {\rm{Si}} \cdot }\\ {({\rm{Si - E^{\prime}}})} \end{array} {\rm{ + }} \def\eqcellsep{&}\begin{array}{@{}*{1}{c}@{}} { \equiv {\rm{Si - O}}^\circ }\\ {({\rm{Si - OHC}})} \end{array} + {{\rm{e}}^ - }\end{equation}…”
Section: Measurement Results and Discussionmentioning
confidence: 86%
“…In this work, the silicate glass contains silicon and boron ions, both of which are prone to produce the corresponding defects after X-ray irradiation. As shown in Figure 2A, silicon oxygen hole center (Si-OHC, ≡Si-O • , g∼2.009), 25 boron oxygen hole center (B-OHC, = B-O • , g∼2.002), 26 and silicon dangling bond (Si-E', ≡Si-, g∼2.001) 27 are found in the irradiated P0 samples. Defects are formed when X-ray photon energy is absorbed by the glass via the following processes [25][26][27] :…”
Section: Emission Behaviors Of Pr 3+ -Doped Silicate Glasses Before A...mentioning
confidence: 85%