Dissociative photoionization cross sections of O2from threshold to 120 Aring;

摘要

The photoionization cross sections for producing the O2+parent ion and the O+fragment ion from neutral O2are presented from 650 to 120 Aring;. A new technique was used that eliminated the serious problem of identifying the true abundance of the O+ions. These ions are generally formed with considerable kinetic energy and because most mass spectrometers discriminate against energetic ions true O+abundances are difficult to obtain. In the present work the relative cross sections for producing O2+are obtained and normalized against the total cross sections in a spectral region where dissociative ionization is not possible. The fragmentation cross sections for O+were then obtained by subtraction of the O2+cross section from the total photoionization cross section.