Production and sharing of 3 dσ - vacancies in heavy systems revisited.. I. Integral cross sections

The results of integral measurements of X-ray yields from Cu + Bi collisions at 0.25 - 1.625 MeV/amu energies are presented. The experiment was performed at the High Voltage FN tandem accelerator of IPNE. Absolute σK (Cu) and σL3 (Bi) ionization cross sections and σLγ (Bi) X-ray production cross sections have been determined by normalizing to the scattered particles at 90o. The experimental data are much larger than SCA predictions for the direct ionization of corresponding atomic orbitals which is in accordance with the main vacancy production mechanism for this collision system in the vicinity of the K-L matching region: ionization at small internuclear distances of the electrons promoted into 3 dσ molecular orbital (MO), followed by vacancy sharing at large distances between 3 dσ - 2 p3/2σ MOs. Accordingly 3 dσ MO ionization cross sections have been determined, which compare favorably with other experimental results on similar system and some theoretical estimation. (Author)