The [formula omitted]–[formula omitted] electronic absorption of cyclopentadienyl peroxy radical (c-C5H5OO[rad]): A cavity ringdown spectroscopic and computational study

Abstract

The electronic absorption spectrum of cyclopentadienyl peroxy radical, c-C5H5OO, has been recorded over the range 7000–8700cm−1 by cavity ringdown spectroscopy. Using electronic structure calculations, the observed features are assigned to the G conformer, with a band origin at 7479cm−1. A second form, the C conformer, is predicted to absorb weakly in a region obscured by signals arising from HO2 radical and cannot be definitively identified. Simulations of the sequence band structure based on computed OOCH torsional potentials suggests that the barrier separating the enantiomeric G/G′ minima is ca. 600cm −1, significantly larger than values predicted by B3LYP/cc-pVDZ (138cm−1) and G2 (314cm−1) calculations.