OZONE SYNTHESIS INDUCED BY ELECTRON-BOMBA RDMENT OF A DIOXYGEN MATRIX

Electron irradiation of a molecular oxygen film leads to ozone formati on. O-3 synthesis was demonstrated by high-resolution electron energy- loss spectroscopy (HREELS) which shows vibrational modes of O-3 molecu les. This identification was confirmed by isotopic effect. The energet ic threshold of O-3 synthesis is of the order of 3.5 eV. This correspo nds to O-2 dissociation by electron attachment: O-2+e(-)-->O(P-3)+O-(P -2), followed by the spontaneous recombination reaction: O+O-2+O-2-->O -3+O-2. Above 5.1 eV bombarding energy, O-2 dissociation via excitatio n of Rydberg states and Schumann-Runge continuum is the main source of atomic oxygen and thus of ozone. Further measurements performed as a function of the irradiation time show that the number of O-3 molecules formed in the film saturates.