Photodissociation of O3 around 309 nm

Abstract

Photodissociation reaction of O3 following ultraviolet photon excitation around the thermodynamic threshold of the dissociation channel of O(1D) + O2(a1Δg) at 309.44 nm has been studied under room-temperature and jet-cooled conditions. Both O(1D) and O(3P) photoproducts are detected by a technique of vacuum ultraviolet laser-induced fluorescence (VUV-LIF) spectroscopy. Photofragment excitation (PHOFEX) spectra for the O(1D) and O(3P) atoms are obtained by scanning the photolysis laser wavelength between 297 and 316 nm while monitoring VUV-LIF signal intensities at 115 and 130 nm for O(1D) and O(3P), respectively. From the behavior of the PHOFEX spectra for the O(3P) and O(1D) atoms around the threshold into O(1D) + O2(a1Δg), the existence of an exit barrier along the O−O2 dissociation coordinate in the photoexcited electronic state of O3 is suggested. Analysis of the line widths in the jet-cooled PHOFEX spectra of O(1D) and O(3P) suggests that the quasi-bound states below the barrier and above the thresho...