Band gap effect on H− ion survival near Cu surfaces

The presence of a band gap in the direction normal to the surface, such as the L-gap in the case of the Cu(1 1 1) surface, should dramatically influence various experimental results on electron capture (loss) in atom-surface collisions. The main goal of this joint theoretical and experimental work is to investigate the impact of the L-gap on the survival probability of hydrogen negative ions interacting with a copper surface. We show that the ion survival probability strongly depends on the collision velocity. At low velocities the electron loss is increased by the collision velocity, whereas at high velocities the Cu(1 1 1) surface behaves like a jellium surface and the shorter the interaction time, the smaller the decay.