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Infrared Spectra of Products of the Reaction of H Atoms with O2 Trapped in Solid Neon: HO2, HO2+, HOHOH, and H2O(HO)

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journal contribution
posted on 18.02.2016, 18:25 by Marilyn E. Jacox, Warren E. Thompson
When a Ne/O2 mixture is codeposited at 4.3 K with a Ne/H2 mixture that has been passed through a microwave discharge, the infrared spectrum of the resulting deposit includes prominent absorptions of the three vibrational fundamentals of HO2 and seven relatively weak absorptions in the infrared and near-infrared, only one of them previously reported, that can be assigned to overtones and combination bands of that product. Similar assignments are made for DO2. A new, broad absorption at 702.9 cm–1 appears close to the gas-phase absorption of HOHOH at 697 cm–1. Isotopic substitution experiments support that assignment. Evidence is also presented for the stabilization of HOHO. Absorptions near the vibrational fundamentals of H2O and an absorption at 3472.4 cm–1 grow on exposure of the deposit to radiation of wavelength shorter than 345 nm. These absorptions are assigned to the H2O­(HO) complex, in agreement with the results of an earlier argon-matrix study. In both studies, photodestruction of HO2 molecules that have H2O trapped in a nearby site results in formation of the complex. Because the discharge through Ne/H2 supports ion production, photodetachment of the resulting HOHOH is an additional source of the complex. Other absorptions may be contributed by the bending fundamental of HO2+ and by a cation complex with H2.