Single- and double-photoionization cross-sections of nitrogen dioxide (NO2) and ionic fragmentation of NO2+ and NO22+

Single- and double-photoionization processes of nitrogen dioxide (NO2) have been studied in the photon energy region of 37-125 eV by use of time-of-flight mass spectrometry and the photoion-photoion coincidence method together with synchrotron radiation. The single- and double-photoionization cross-sections of NO2 are determined. Ion branching ratios and the partial cross-sections for the individual ions, respectively, produced from the parent NO22+ and NO22+ ions are also determined separately at excitation energies where the molecular and dissociative single- and double-photoionization processes occur simultaneously. It was found that dissociation of the parent ions is dominant both in single and double photoionization. The thresholds for the O+ + NO+ and N+ + O+ dissociation channels of NO22+ are at 35.0 +/- 0.3 and 43.6 +/- 0.3 eV, respectively. Kinetic energy releases in these two dissociation 2 channels of NO22+ have also been elucidated. (C) 2004 Elsevier B.V. All rights reserved.