High resolution K-edge spectroscopy of oxygen transient species: excitation of the metastable O2 a1Dg molecule and the O(3P) atom

The K-edge photoionization spectra of metastable O2 (a1?g) molecules and O (3P) atoms have been investigated at high resolution. Both species were prepared on-line using a microwave discharge. For the molecule the transition to the ?* 1? state has been identified below the ionization threshold, using total-ion-yield spectroscopy. Above the edge the previously unobserved 2? state of the O2+ core-hole ion has been located by photoelectron spectroscopy. The results provide a link between the singlet and triplet manifolds of the core excited states of the oxygen molecule. The 1s excited states of the oxygen atom were also studied. The high resolution allowed the characterization of higher members of the Rydberg series and first linewidth measurements for those transitions.