MATRIX REACTIONS OF BORON ATOMS WITH OXYGEN MOLECULES. INFRARED SPECTRA OF SEVERAL BORON-OXYGEN SPECIES
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Date
1991
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Ohio State University
Abstract
Boron atoms from YAG laser ablation of the solid have been codeposited with Ar/$O_{2}$ samples on a 12K salt window. The product infrared spectrum was dominated by 3 strong $11_{g}$ isotopic bands at 1299.3, 1282.9 and $1274.6 cm^{-1}$ with $^{10}B$ counterparts at 1347.6, 1330.7 and $1322.2 cm^{-1}$. Oxygen isotopic substitution ($^{16}O^{18}O$ and $^{18}O_{2}$) confirms the linear $BO_{2}$ assignment of these strong bands. A sharp medium intensity band at 1854.7 has appropriate isotopic ratios for BO, which exhibits an 1862 $cm^{-1}$ gas phase fundamental. A sharp $1931.0 cm^{-1}$ band shows isotopic ratios appropriate for another linear $BO_{2}$ species; correlation with spectra of ${BO_{2}}^{-}$ in alkali halide lattices confirms this assignment. A weak $1898.9 cm^{-1}$ band grows on annealing and shows isotopic ratios for a BO stretching mode and isotopic splittings for 2 equivalent B and O atoms, which confirms assignment to $B_{2}O_{2}$. Weak 2062, 2048 and 2017 $cm^{-1}$ bands grow markedly on annealing and show isotope shifts appropriate for a terminal -B0 group interacting with one other oxygen; these bands are assigned to $B_{2}O_{3}$ in agreement with the Weltner and White groups. The present experiments demonstrate that new boron-containing molecular species can be formed by matrix reactions of boron atoms and suitable molecules. These studies show that charged species can also be produced by pulsed laser ablation.
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Author Institution: Department of Chemistry, University of Virginia