A STUDY OF THE ABSOLUTE PHOTOABSORPTION, PHOTOIONIZATION AND PHOTODISSOCIATION CROSS-SECTIONS AND THE PHOTOIONIZATION QUANTUM EFFICIENCY OF OXYGEN FROM THE IONIZATION THRESHOLD TO 490 ANGSTROM

The absolute photoabsorption, photoionization and photodissociation cross sections and the photoionization quantum efficiency of oxygen have been measured using a double ion chamber and monochromated synchrotron radiation. In addition to structure associated with well established Rydberg series, some new features have been observed which are interpreted in terms of transitions into Rydberg states converging onto the 3 2PI(u) ionization threshold. The photoionization quantum efficiency measurements indicate that the decay of Rydberg states by dissociation into neutral products is a significant de-excitation route, particularly for the low vibrational members of the H 3PI(u). state. A sum rule analysis has been carried out by combining the present absolute photoabsorption measurements with similar data covering the remaining wavelength regions.