Projectile-ionization cross sections for H-like ions in collisions with N2, O2, Ne, and Ar targets

Electron-loss cross sections for hydrogen-like ions with atomic number Z1 (2≤Z1≤7) and with velocity v (0.3v0approx. <v/Z1approx. <6v0; v0 is the Bohr velocity) are investigated in collisions with N2, O2, Ne, and Ar targets using the unitarized impact-parameter method. In order to describe the form factors of these targets, we use the modified Moliere electron distributions where the parameters appearing in the Moliere potential are slightly modified to fit the form factors obtained from Hartree-Fock wave functions in the small momentum-transfer region. Then we find the electron-loss cross sections sensitive to those parameters at high velocities. The scaling relations, characterized by the reduced cross section sigma ( = Z1/sup m/σ) versus the reduced velocity v ( = v/Z1), are presented, where m = 2.8 for N2 and O2, 2.6 for Ne, and 2.4 for Ar. Here the molecular effect in N2 and O2 targets and the polarization of target electron clouds due to a projectile are both neglected. These scalings yield good agreement with the reported data, particularly when vapprox. <1