Projectile excitation in the collision of Arq+(q=1, 2 and 3) with He and Ne

Abstract
Cross sections for radiative emission from Ar II (3p44s 2P), Ar II (3p43d 2D), Ar II (3s3p6 2S), Ar III (3s3p5 1P) and Ar III (3s3p5 3P) projectile states have been measured for Arq+ (q=1, 2 and 3) ions colliding with He and Ne at impact energies between 15 and 400 keV. The experimental results are explained qualitatively by considering the MO correlation diagrams and potential energy state diagrams. It is often found that the cross section for excitation decreases with the increase of the number of intermediate transitions required in order to reach the excited state. When there is a mechanism involving radial coupling leading from initial to final states then the measured emission cross section decreases with energy, whereas mechanisms involving rotational coupling lead to cross sections that increase with increasing energy up to 200 keV or more.