Velocity dependence of stabilized double electron capture in N 7+Ar collisions

Abstract

We have studied the two-electron processes in the collision of N 7+ with argon at various energies. We have measured the radiative stabilization P rad, defined as the ratio of the true double capture σ TDC to the total double capture which is the sun of σ TDC and the autoionizing double capture σ ADC. A large enhancement of P rad (17–44%) with decreasing projectile velocity (0.6–0.14 a.u.) has been found. On the other hand, by using the photon-ion coincidence technique to select the double capture processes, we have observed an increase of the emission cross sections of optical transitions from (3, n) Rydberg states with decreasing projectile energy. We give a tentative explanation which is based on a combination of autotransfer to Rydberg states and the postcollisional “satellisation” of the Rydberg electron described by Roncin and Kazansky.