On the 1S → 1D emission of O by exciting O2 into and beyond the Schumann-Runge continuum in Ar matrices at 15 K

The excitation spectrum of a stable photoproduct of O2 is recorded by monitoring the 1S → 1D emission of O in Ar matrices at 15 K between 200 and 100 nm. The time evolution and changes in intensity of the 1S → 1D emission of O at different excitation energies indicate the presence of a stable species of O in Ar matrices. It is proposed that the stable species which disappears upon warming to 30 K is O(3P). When irradiated at 140 nm the 1S → 1D emission intensity of O increases and irradiation at 121 nm results in the bleaching of this emission. Based on the present study and theoretical data, the possibility that this species could be O2 in a metastable site or O(1D) in Ar matrices is ruled out.