First direct proof of internal conversion between bound states - art. no. 024311

We present direct evidence for the process of internal conversion between b ound atomic states (BIC) when the binding energy of the converted electron becomes larger than the nuclear transition energy. This process has been pr oposed as an explanation of the measured, unexpectedly short lifetime of th e first excited state of Te-125 with charge state larger than 44(+). We hav e detected the K-alpha x rays emitted in flight which follow the filling of the K-shell vacancy created by the bound internal conversion process, toge ther with gamma rays from Te ions in charge states ranging between 44(+) an d 48(+). For Te45+ and Te46+, the comparison of the x-ray to gamma-ray rati os with the theoretical calculations of the internal conversion coefficient s including decay to bound atomic states, assuming Te ions in their ground electronic state, show poor agreement. The agreement becomes good if accoun t is taken of BIC decay of excited initial states with different occupancie s of the 2p(1/2) and 2p(3/2) subshells. In this situation, the half-life be comes sensitive to the precise initial state and simple specification of th e charge state alone is no longer appropriate.