Ionic Fragmentation of NO Following Excitation of the NK-Shell and the OK-Shell Electron

Ionic fragmentation of NO stimulated by soft X-ray absorption has been studied using a monochromatized synchrotron radiation and a time-of-flight mass spectrometer. In photoexcitation of a 1s electron, the singly charged molecular ion NO+ was formed only at 410 and 533 eV (transitions to the 2π orbital), and a fragment ion N+ had the highest intensity in all the energies. The doubly charged molecular ion was produced appreciably, and fragment ions (N2+ and O2+) were formed considerably even below the 1s ionization thresholds. The measured time-of-flight spectra were converted into kinetic energy distributions of N+, O+, N2+ and O2+ at photon energies for characteristic excitation by a simulation calculation. The dissociation pathways from the core-hole states of NO were discussed using the kinetic energy distribution and ion intensity ratios as well as Auger electron spectra in the literature.