Photoionization study of NO2. I. The ionization potential

Abstract
The ionization potential of NO2 has been redetermined by photoionization mass spectrometry. The photoionization efficiency curve exhibits autoionization in the threshold region, allowing the assignment of an upper limit on the ionization potential of 9.62 eV. This result combined with the results of other groups brackets the ionization potential between 9.62 and 9.25 eV, most probably closer to the upper limit.