Spectral distribution of the 2S →1 S two-photon transition in atoms and few-electron ions

摘要: The two-photon decay of the 2S state to ground in dressed atoms and one- or two-electron ions has been studied for several decades. Relativistic calculations have shown an Z-dependence spectral shape this transition ions. We measured distribution 1s2s \(^1\!S_0\) → 1s 2 He-like tin at ESR storage ring using a new approach such experiments. In method, relativistic collisions initially Li-like projectiles with gaseous target were used populate exclusively first excited state, 1s2s, tin, which provided clean spectrum. was compared fully calculations. obtained results show very good agreement tin.