Measurement of Auger electrons emitted through Coster–Kronig transitions under irradiation of fast C 2 + ions

We measured the yield of Auger electrons emitted through Coster–Kronig transitions from Rydberg states $1s2p\left({}^{3}P\right)\mathrm{nl}$ ($n=7,8$) and $1s^{2}2p\left({}^{2}P\right)\mathrm{nl}$ ($n=5,6,7$) of emergent atomic ions ${\text{C}}^{q+}$ under irradiation of 3.5-MeV/atom C⁺ and ${\text{C}}_2^{+}$ ions on thin C foil targets. The Auger electron yields are suppressed for ${\text{C}}_2^{+}$ irradiation compared with C⁺ irradiation and the relative yield becomes larger as n increases. Thus, amount of scattered electrons having lower relative energy in the projectile rest frame becomes larger. The results obtained in this study support the influence of projectile velocity on the cluster effect of secondary electron yields.