Fluroescence excitation function of Ni 1200-Å and cross sections for fluorescence photon-photoion coincidence produced through photoexcitation of N2

The absolute fluorescence excitation function of the Ni 1200-Å emission through photoexcitation of N₂ has been measured in the 250-620 Å region using synchrotron radiation as the continuous tunable light source. The dissociative photoionization excitation of N₂ involving the production of Ni 1200-Å emission and N⁺ ion has also been studied at several selected photon wavelengths shortward of 360 Å using a coincidence technique to detect the Ninfireset 1200-Å fluorescence photon and the N⁺ ion. The maximum quantum yields for producing these processes are of the order of 6×10^-2. It was found that dissociative excitation processes can be competitive with the dissociative ionization excitation processes for the multiple-electron transition states. The present results suggest that the electronic states of N₂ in the 320-340 Å region consist of both ion states of N⁺₂ (Langhoff et al., 1981) and neutral states of N₂, which could be the Rydberg states converging to N⁺⁺₂ (Sambe and Ramaker, 1986).