DECAY OF HOLLOW ATOMS ABOVE AND BELOW A SURFACE

We present some experiments which demonstrate definitively that the fi lling of the L shell of argon hollow atoms formed below a surface proc eeds, like those formed above a surface, through a cascade of eight sp ontaneous transitions. This result means that the hollow atoms' clock property may be used in both cases to study continuously the approach and penetration of an ion onto a surface as it is experimentally shown .