The A∼-X∼ electronic absorption of cyclopentadienyl peroxy radical (c-C5H5OO): A cavity ringdown spectroscopic and computational study

► Organic peroxy radicals are important reactive chemical intermediates in tropospheric oxidation and combustion. ► Cavity ringdown spectroscopy is employed to observe the NIR electronic spectrum of cyclopentadienyl peroxy. ► The origin and several vibrational bands of the c-C5H5O2 G conformer are observed and assigned.