IONIZATION AND DISSOCIATION OF N-2 AND CO IN COLLISIONS WITH 2.3Q-KEV AR-Q+ (8-LESS-THAN-OR-EQUAL-TO-Q-LESS-THAN-OR-EQUAL-TO-14)

The charge-state and energy distribution of molecular ions and fragments produced in low-energy, highly-charged-argon-ion collisions with N-2 and CO were measured. Ar-q+ (8 less than or equal to q less than or equal to 14) ions produced by an electron-beam ion source and extracted at 2.3 kV interacted with a molecular-target gas jet located in the ionization region of a time-of-flight spectrometer. The resulting molecular recoils and fragments were analyzed by time of flight. For a given molecular target, the measured spectra are all similar and do not depend on the incident argon-projectile charge state. The spectra are dominated by the singly charged ion, either N-2(+) or CO+. The stable or long-lived metastable doubly charged molecular ion CO2+ is the second most prominent feature in Ar-q+ On the CO spectra. Similarly, N-2(2+), which cannot be distinguished from N+, is also presumed to be present in Ar-q+ on the N-2 spectra. The remaining peaks are associated with the dissociation of the N-2(Q+) and COQ+ (2 less than or equal to Q less than or equal to 6) molecular ions formed in the collision. The peak positions correspond to fragments of a given mass-to-charge ratio and kinetic energy calculated assuming vertical target ionization.