Photoelectric Properties of Mg2Si, Mg2Ge, and Mg2Sn II. UV Excitation

In the previous paper (I) the energy distribution spectra of photoelectrons (XPS) and Auger electrons (AES) excited with AlKα radiation in Mg2Si, Mg2Ge, and Mg2Sn were presented. Here similar measurements are reported performed with He resonant radiation (48.4, 40.8, and 21.2 eV). The effect of surface contamination by O2 or H2O is shown to be very important in these UPS spectra and results meaningful of the material under study can only be obtained if such contamination is kept to less than 0.2 monolayers. The strong structure which appears in less clean samples has been identified as related to the compounds MgO and Mg(OH)2. The UPS spectra of the clean materials yield information about the densities of valence states and about the outermost d electrons of the Ge and Sn core. Very accurate values for the corresponding spin‐orbit splittings and chemical shifts are obtained.