Stabilized Hollow Atoms (Ions) Produced with Multiply Charged Ions Passed through Microcapillaries

Ions of 9 keV/u Ne 9+ are impinged upon a microcapillary target along the capillary axis. X-rays emitted from the projectile downstream of the target show that a part of ions are in multiply excited states keeping a K-shell orbital open, i.e., hollow atoms (ions) are extracted in vacuum . Further, a considerable fraction of them are in extremely stabilized states with lifetimes of ∼ns which is more than 10 6 times longer than typical lifetimes of a Ne K-hole. A theoretical prediction suggests that core configurations with high spin multiplicities such as 1s2s2p 4 P are potential candidates of the stabilized fraction.