| Popis: |
In the measurements of emission of photon pairs from many‐electron atomic systems with a vacancy in the K shell (xx decay) resonance effect was observed. The effect was predicted by the second‐order perturbation theory of xx decay in which summation over virtual intermediate states is carried out not only over unoccupied bound and over unbound states, but also over occupied bound states. Stationary intermediate states between the initial and final state, which are a path for ordinary cascade emission of two photons (x rays), cause a large increase of the differential transition probability when energy of the photons due to xx decay approaches values of cascade photons. The effect was observed in 3d→1s xx decay of K‐shell‐vacancy states in silver and hafnium atoms. |
