Radiative resonant energy transfer: A new excitation process of beam-foil interaction

Evidence is provided for radiative resonant energy transfer (RRET) from bulk plasmons to discrete states for the first time. The difference of the excitation mechanisms of the 1s2s 3S1 and 1s2p 3P2o states in He-like Ti ions on target nuclear charge have been studied by the beam-two-foil technique. We observed that the 1s2s 3S1 states are mostly populated with an aluminum target where as the 1s2p 3P2o states with a carbon target. The 1s2s 3S1 states produced with a carbon target are further excited to 1s2p 3P2o state, but this type of excitation does not occur with an aluminum target. This excitation mechanism is attributed to resonant energy transfer from bulk plasmons in the carbon target. Furthermore, the resonant process is confirmed by observation that the 1s2s 3S1 states populate more than the 1s2p 3P2o states with He-like V, Fe and Ni ions even with carbon targets.