The detachment of electrons from negative ions

Measurements have been made of collision detachment cross-sections for O– in O2, N2, H2O, H– in H2, O– in O2 and Cl– in Cl2 between 10 and 2500 eV. Values obtained, ~ 5 x 10–16 cm2 at 10 eV, make it likely that this detachment process is of significance in the removal of negative ions from positive columns of discharges where such energies may be found. It is possible to distinguish qualitatively between a detachment and a charge transfer collision, and in all cases studied except in O2–, in O2, the charge transfer is found to be negligible.