Mercuric oxide is a well-known and stable solid, but the diatomic molecule Hg-O is very fragile and does not survive detection in the gas phase. However, laser ablation of Hg atoms from a dental amalgam alloy target into argon or neon containing about 0.3 % of 16 O2 or of 18 O2 during their condensation into a cryogenic matrix at 4 K allows the formation of O atoms which react on annealing to make ozone and new IR absorptions in solid argon at 521.2 cm-1 for Hg-16 O or at 496.4 cm-1 for Hg-18 O with the oxygen isotopic frequency ratio 521.2/496.4=1.0499. Solid neon gives a 529.0 cm-1 absorption with a small 7.8 cm-1 blue shift. CCSD(T) calculations found 594 cm-1 for Hg16 O and 562 cm-1 for Hg18 O (frequency ratio=1.0569). Such calculations usually produce harmonic frequencies that are slightly higher than the anharmonic (observed) values, which supports their relationship. These observed frequencies have the isotopic shift predicted for Hg-O and are within the range of recent high-level frequency calculations for the Hg-O molecule. Spectra for the related mercury superoxide and ozonide species are also considered for the first time.
Keywords: Hg−O diatomic molecule; matrix-isolation spectroscopy; mercury; ozonides; superoxide.
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