skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Electron trapping and hydrogen atoms in oxide glasses

Abstract

Trapped hydrogen atoms generated in 3 MeV [beta]-radiolysis of B[sub 2]O[sub 3]:OH glass below 140 K were studied using electron paramagnetic resonance (EPR). Two types of trapped H atoms were present in this glass; one was an interstitial atom located in a void between several BOB fragments, another was the atom trapped in a cage between two B[sub 3]O[sub 6] (boroxol) rings connected by hydrogen bonds. The geometry of the trapping site was determined using electron spin echo envelope modulation (ESEEM) spectroscopy. Time-resolved pulsed EPR was used to observe mobile H atoms at 300[endash]500 K. The lifetimes (10[endash]100 [mu]s) of the H atoms were controlled by [approximately]10[sup 18] hthinsp;cm[sup [minus]3] of metastable spin centers. The H atoms migrated with diffusion constant of 1.5[times]10[sup 7] hthinsp;cm[sup 2]/s (activation energy of 0.13[endash]0.16 eV), mean residence time at the site of 4[endash]5 ns, and mean jump length of 0.56 nm (at 300 K). This site-to-site migration causes rapid spin relaxation due to modulation of magnetic interactions, such as dipole[endash]dipole interaction of the unpaired electron of the H atom with [sup 10]B and [sup 11]B nuclei. Though there was no observed H/D kinetic isotope effect on the decay/diffusion of the hydrogen atoms, there wasmore » a significant isotope effect on their radiolytic yield ([alpha][approx]1.5[endash]1.6). This effect is comparable to the one observed in SiO[sub 2]:OH and aqueous acid glasses. This similarity suggests that in the room-temperature [open quotes]wet[close quotes] SiO[sub 2] and B[sub 2]O[sub 3] glasses, mobile H atoms are generated via electron trapping at the proton(s) associated with threefold coordinated oxygen ([endash]OH[sub 2][sup +] and/or [gt]OH[sup +] centers). Semiempirical MNDO simulations were used to estimate energetics of such electron trapping reactions.« less

Authors:
; ; ;  [1]
  1. (Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States))
Publication Date:
OSTI Identifier:
6432673
Alternate Identifier(s):
OSTI ID: 6432673
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 111:11; Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; BORON COMPOUNDS; BOROSILICATE GLASS; ELECTRON SPIN RESONANCE; HYDROGEN; HYDROXYL RADICALS; IMPURITIES; INTERSTITIALS; OXYGEN COMPOUNDS; RADIATION CHEMISTRY; RADIOLYSIS; TRAPPED ELECTRONS; TRAPPING; CHEMICAL RADIATION EFFECTS; CHEMICAL REACTIONS; CHEMISTRY; CRYSTAL DEFECTS; CRYSTAL STRUCTURE; DECOMPOSITION; ELECTRONS; ELEMENTARY PARTICLES; ELEMENTS; FERMIONS; GLASS; LEPTONS; MAGNETIC RESONANCE; NONMETALS; POINT DEFECTS; RADIATION EFFECTS; RADICALS; RESONANCE 400600* -- Radiation Chemistry

Citation Formats

Shkrob, I.A., Tadjikov, B.M., Chemerisov, S.D., and Trifunac, A.D. Electron trapping and hydrogen atoms in oxide glasses. United States: N. p., 1999. Web. doi:10.1063/1.479740.
Shkrob, I.A., Tadjikov, B.M., Chemerisov, S.D., & Trifunac, A.D. Electron trapping and hydrogen atoms in oxide glasses. United States. doi:10.1063/1.479740.
Shkrob, I.A., Tadjikov, B.M., Chemerisov, S.D., and Trifunac, A.D. Wed . "Electron trapping and hydrogen atoms in oxide glasses". United States. doi:10.1063/1.479740.
@article{osti_6432673,
title = {Electron trapping and hydrogen atoms in oxide glasses},
author = {Shkrob, I.A. and Tadjikov, B.M. and Chemerisov, S.D. and Trifunac, A.D.},
abstractNote = {Trapped hydrogen atoms generated in 3 MeV [beta]-radiolysis of B[sub 2]O[sub 3]:OH glass below 140 K were studied using electron paramagnetic resonance (EPR). Two types of trapped H atoms were present in this glass; one was an interstitial atom located in a void between several BOB fragments, another was the atom trapped in a cage between two B[sub 3]O[sub 6] (boroxol) rings connected by hydrogen bonds. The geometry of the trapping site was determined using electron spin echo envelope modulation (ESEEM) spectroscopy. Time-resolved pulsed EPR was used to observe mobile H atoms at 300[endash]500 K. The lifetimes (10[endash]100 [mu]s) of the H atoms were controlled by [approximately]10[sup 18] hthinsp;cm[sup [minus]3] of metastable spin centers. The H atoms migrated with diffusion constant of 1.5[times]10[sup 7] hthinsp;cm[sup 2]/s (activation energy of 0.13[endash]0.16 eV), mean residence time at the site of 4[endash]5 ns, and mean jump length of 0.56 nm (at 300 K). This site-to-site migration causes rapid spin relaxation due to modulation of magnetic interactions, such as dipole[endash]dipole interaction of the unpaired electron of the H atom with [sup 10]B and [sup 11]B nuclei. Though there was no observed H/D kinetic isotope effect on the decay/diffusion of the hydrogen atoms, there was a significant isotope effect on their radiolytic yield ([alpha][approx]1.5[endash]1.6). This effect is comparable to the one observed in SiO[sub 2]:OH and aqueous acid glasses. This similarity suggests that in the room-temperature [open quotes]wet[close quotes] SiO[sub 2] and B[sub 2]O[sub 3] glasses, mobile H atoms are generated via electron trapping at the proton(s) associated with threefold coordinated oxygen ([endash]OH[sub 2][sup +] and/or [gt]OH[sup +] centers). Semiempirical MNDO simulations were used to estimate energetics of such electron trapping reactions.},
doi = {10.1063/1.479740},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = ,
volume = 111:11,
place = {United States},
year = {1999},
month = {9}
}