Resonant coherent excitation of hydrogen-like Ar ions to the n=3 states

We have succeeded in observing resonant coherent excitaion (RCE) of Is elec trons to the n = 3 states in 390 MeV/u hydrogen-like Ar17+ ions planar chan neled in a silicon crystal through measurements of the charge-state distrib ution of ions transmitting the crystal. Furthermore, we directly confirmed RCE to the n = 3 states by observing the enhancement of the de-excitation X -rays, i.e., K-beta X-rays under the resonance condition. The resonance pro files of the charge-state distribution as functions of the incident angle t o the crystal, which uniquely relates with the transition energy, have a ch aracteristic structure consisting of several peaks. Compared with the profi le of RCE to the n = 2 states, the present profiles show a large peak shift from the j = 1/2 and 3/2 levels in vacuum, and the profiles are much wider than those expected from the Stark-split. level structure of the n = 3 man ifolds due to the position(distance from the channel center in the planar c hannel) dependent strong static field in the crystal.