Hydrogenic Lamb shift in iron Fe25 and fine-structure Lamb shift

Abstract

1s-2p Lyman α transitions in hydrogenic iron Fe25+ have been observed from a beam-foil source in fourth-order diffraction off ADP 101 and PET 002 crystals, simultaneously with the n=2 to n=4 Balmer β transitions diffracted in first order. Calibration of the local dispersion relation of the spectrometer using Balmer β lines provides measurements of Lyman α wavelengths. The approach of fitting the full two-dimensional dispersion relation, including other members of Balmer and Lyman series, limits random and systematic correlation of parameters, and reveals a major systematic due to dynamical diffraction depth penetration into a curved crystal. The development of a theory of x-ray diffraction f..