Direct detection and spectroscopy of O4*
Abstract
We have produced and directly detected a metastable state of tetraoxygen in a molecular beam, both by means of a dc discharge and by photodissociation of ozone in the collision region. The O4* produces a complex spectrum from which general conclusions may be made about its energetics and structure. The detection proceeds through a (1+1) resonant photoionization process in the vicinity of 300 nm, implying an energy for this species about 4 eV above that of two isolated O2 molecules. A predominance of peak frequency differences in the range 411–419 cm-1 supports a cyclic D2d geometry as predicted by abinitio calculations, although a definitive judgment on the structure of O4* awaits further study.