Rydberg-to- M -shell x-ray emission of hollow Xeq+ (q=27-30) atoms or ions above metallic surfaces RYDBERG-TO- M -SHELL X-RAY EMISSION of HOLLOW ... Z. Y. SONG et al.

X rays originating from transitions from high Rydberg states to the M shell (here called Rydberg-to-M-shell x rays) have been measured in the interaction of Xeq+ (q=27-30) ions with aluminum, molybdenum, and beryllium surfaces in the energy range of 350-600 keV, by using a Si(Li) detector. The transition energy calculation by Cowan's program with relativistic correlation indicates that such x rays are mainly from the transition of the higher quantum states, with the principal quantum number from 6 up to 30, directly to M shell of xenon. The yield of the x ray per vacancy in M shell decreases slightly with increasing the projectile energies and is inversely proportional to the work functions of metallic surfaces used. However, it increases rapidly with the increase of the projectile charge states. All of these experimental facts combined with the transition rate calculations indicate that the measured Rydberg-to-M-shell x rays come from the "above the surface" hollow Xe atoms or ions deexcitation, when the inner shells such as N and O have not been filled.