Electron Excited M X-Ray Spectra of the Elements 55≤Z≤58

Abstract.

The M emission spectra of the elements 55 Cs, 56 Ba, 57 La, and 58 Ce were measured using wavelength dispersive X-ray spectrometry with a TAP crystal as the dispersing element. In total, 34 M lines were observed, of which only 13 are contained in the compilation of Bearden. Mα and Mβ of 56 Ba are among the new lines. They have their origin in a similar process to one that is known for 57 La. The interpretation of these spectra is complicated by the strong overlap of some emission lines with the M_IV,V absorption structures, which may lead to anomalous self-absorption effects. Therefore, we have concentrated on spectra taken at a low energy of the exciting electrons, E₀=2.5 keV. However, in order to illustrate the anomalous self-absorption effects parts of the 2.5 keV spectra, of Ba and La, are shown in comparison with the 10 keV spectra.