Radiative electron capture to continuum in relativistic ion–atom collisions

The capture of a target electron to the projectile continuum with simultaneous photon emission, known as radiative ionization (RI), is investigated theoretically for fast, highly charged projectiles colliding with light target atoms. Based on the impulse approximation in its post form, the features of radiative ionization are studied and contrasted with the related processes of radiative electron capture and nonradiative electron capture to continuum (ECC). A large RI cusp asymmetry is found, increasing strongly with projectile charge but decreasing with projectile velocity. However, in contrast to ECC, the cusp is skewed to the high-energy side. Results are shown for 20 MeV amu−1 Kr36+ + H and for 100 and 400 MeV amu−1 U92+ on H and N.