The M Emission Spectrum of 68Erbium

The M emission spectrum of 68Er was reinvestigated using wavelength dispersive spectrometry, with a TAP diffracting crystal. By recording the spectra using the second-order reflection, an improved energy resolution was achieved, which is necessary to resolve the M5O3 line from the neighboring alpha M5N7 transition. In addition to the five lines/bands tabulated in the classical paper of Bearden, a number of further lines were observed. These are M1N3, M3O1, M2N1, M5O3, M3N1, and M4N3. For all the lines with an energy below the M5 absorption structure (M5O3, M3N1, M4N3, and zeta M5N3), an increasing relative intensity with increasing energy of the exciting electrons, E0, was observed. This dependence has its origin in the fact that these lines are normally absorbed whereas Malpha (M5N7) and Mbeta (M4N6) are additionally affected by anomalous line-type absorption.