Observation of enhanced zero-degree binary encounter electron production with decreasing charge-state q in 30 MeV Oq+ + O2 collisions

We have measured binary encounter electron production in collisions of 30 MeV Oq+ projectiles (q=4-8) and O2 targets. Measured double differential BEe cross-sections are found to increase with decreasing charge-state q, in agreement with similar previously reported zero-degree investigations for H2 and He targets. However, measurements for the same system but at 25 degrees shows the opposite trend, that BEe cross sections decrease slightly with decreasing charge state