Studies of photoionization and photodissociation of N2in 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 synchrotron facility MAX in Lund was used to produce N 2 + and N + ions from a N 2 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 N 2 + spectra show a rich structure originating from autoionizing Rydberg series in N 2 converging to the A and B states in N 2 + . Line structures around 24eV in the N 2 + spectrum as well as in the N + fragment spectrum are attributed to autoionization and dissociation respectively, of doubly excited Rydberg states in N 2 converging to the N 2 + C state. Broad features appear in the N + spectrum accompanied by sharp onsets at the second and third dissociation limits in N 2 + . These are interpreted as dissociation channels via N 2 + states.