TRUE DOUBLE CAPTURE IN COLLISIONS OF BARE AND HYDROGENLIKE IONS WITH RARE-GAS ATOMS (Z=7-13)

We measured relative cross sections for true double capture (TDC) and autoionizing double capture (ADC) in the collisions of slow bare Z(Z)+ and hydrogenlike Z(Z-1)+ ions (Z=7-13) on rare gases. We found that the probabilities for radiative stabilization P(rad) = sigma(TDC)/(sigma(TDC)+sigma(ADC)) are much stronger when the binding energies of the projectile captured electrons are comparable to those of the limits of the Rydberg (3,n), (4,n), and (5,n) series. The observed strong effect of the projectile core on the probabilities for radiative stabilization of both electrons shows that the relaxation processes of the Rydberg electron play an important role.