Relative efficiencies of symmetrical and asymmetrical collisions inAr+-induced AlL23Auger yields

Computer simulation with the m a r l o w e program is used to study the relative contributions of symmetrical and nonsymmetrical collisions to the Auger $L_{23}$ emission from an aluminum solid target irradiated by low- (5 keV) and high- (50 keV) energy argon ions. The inner-shell ionization process is considered to take place when the distance of closest approach between two collision partners gets smaller than a certain threshold distance which does not have to be the same in both symmetrical (Al-Al) and asymmetrical (Ar-Al) collisions. After cross checking the emission threshold measurements, the theoretical and experimental estimates of ionization thresholds in gases, absolute Auger yield measurements, and computer simulations using the ionization threshold as a parameter, it was found that the threshold distances for the symmetrical and asymmetrical collisions are 0.36 and 0.44 Å, respectively. The relative contribution to Auger emission of both kinds of collisions was substantial, both with 5 and 50 keV incident energy.