Single- and double-photoionization cross sections of nitric oxide (NO) and ionic fragmentation of NO+ and NO2+

Abstract

Single- and double-photoionization processes of gaseous nitric oxide (NO) have been studied in the photon energy region 37\char21{}100 eV by use of time-of-flight mass spectrometry and a photoion-photoion-coincidence method together with synchrotron radiation. The single- (${\mathrm{\ensuremath{\sigma}}}^{+}$) and double- (${\mathrm{\ensuremath{\sigma}}}^{2+}$) photoionization cross sections of NO are determined. Dissociation ratios of the precursors ${\mathrm{NO}}^{+}$ and ${\mathrm{NO}}^{2+}$ are determined separately at the excitation energies where the single and double photoionization are in competition. The results show that the metastable ${\mathrm{NO}}^{2+}$ ions amount to about 15% at higher photon energies in the double-photoionization processes. Ionic branching ratios and the partial cross sections for the individual ions produced from the precursors ${\mathrm{NO}}^{+}$ and ${\mathrm{NO}}^{2+}$ are also presented. The threshold for the dissociative double photoionization was found to be 41.0\ifmmode\pm\else\textpm\fi{}0.5 eV.