Photoionization of N2, O2, NO, CO, and CO2by Soft X Rays

摘要

The total and relative abundances of thermal energy ions produced by absorption of 0.28, 1.25, and 1.5 keV x rays in N2, O2, NO, CO, and CO2and the dissociative ionization cross sections at these energies were measured using a masshyphen;spectrometric technique. The results demonstrate that there is a significant change in the character of the ionization at theKhyphen;absorption edges of the atomic constituents. At these energies dissociative ionization predominates for all the molecules accounting for over 95percnt; of the ions formed at energies above theKedge. Quasistable doubly charged molecular ions make a significant contribution to the thermal energy ions at energies above theKedge. Our results for the total abundances of thermal singly and doubly charged molecular ions are compared with recent measurements by Carlson and Krause.