STUDIES OF PHOTOIONIZATION AND PHOTODISSOCIATION OF N-2 IN THE 15-30 EV REGION USING INTENSE SYNCHROTRON RADIATION

Tunable monochromatic radiation with a spectral flux of 10(12) photons/s . mA . mrad (0.1% bandwidth) from the Swedish synchroton facility MAX in Lund was used to produce N2+ and N+ ions from a N2 target at low pressure. The ions were mass selected in a quadrupole mass spectrometer and the ion production rate was measured as a function of the photon energy with a band pass of 8 meV in the range 15-35 eV. The N2+ spectra show a rich structure originating from autoionizing Rydberg series in N2 converging to the A and B states in N2+. Line structures around 24 eV in the N2+ spectrum as well as in the N+ fragment spectrum are attributed to autoionization and dissociation respectively, of doubly excited Rydberg states in N2 converging to the N2+ C state. Broad features appear in the N+ spectrum accompanied by sharp onsets at the second and third dissociation limits in N2+. These are interpreted as dissociation channels via N2+ states.