Absorptions between 3000 and 5500 cm–1 of Cyclic O4 + and O4 – Trapped in Solid Neon

Recently, gas-phase absorptions in the 3000–4300 cm–1 spectral region have been assigned to combination bands built on (ν1 + ν5) of ground-state cyc-O4 +. Other gas-phase experiments identified an electronic transition of cyc-O4 – complexed with an argon atom between 4000 and 5300 cm–1. Absorptions that correspond closely to these two groups of bands have been observed in neon-matrix experiments in which both cyc-O4 + and cyc-O4 – are trapped at 4.3 K in solid neon. The results are compared with the gas-phase data, and the proposed assignments are considered by taking into account the results of isotopic substitution.