Electron correlation in the formation of hollow states along the Li-like isoelectronic sequence.

ABSTRACT

Hollow-state (double K-shell vacancy) production in Li-like Be+, B2+, C3+, and F6+ ions colliding with He has been investigated using high-resolution Auger-electron spectroscopy. The formation of discrete states and their relative intensities show striking dependences on the nuclear charge Z of the ion. From the projectile velocity dependences of these states the contribution of the electron-electron interaction is determined, showing that the hollow states are formed largely by electron correlation with a strength that diminishes for increasing Z.