X-Ray Line Absorption in theM-Series for 62-Sm

The $M_{\mathrm{IV}}$ and $M_{\mathrm{V}}$ absorption edges for 62-Sm were studied by use of evaporated films of ${\mathrm{Sm}}_2$ ${\mathrm{O}}_3$ and Sm${\mathrm{Cl}}_3$. In view of data in the literature on $M$-absorption of the rare earths 70-Yb and 68-Er, it seemed possible that absorption lines would be found corresponding to transitions in which electrons from the $M$-shell are lifted to the inner $N_{\mathrm{VII}}$ and $N_{\mathrm{VI}}$ levels. When thin absorption films were employed, the entire absorption had the appearance of lines, but thick films revealed the definite edge-like character of the absorption. The $M_{\mathrm{IV}}$ and $M_{\mathrm{V}}$ edges are very similar and are both complex, four edges being distinguished in each case. In both cases the first pair of edges is separated from the latter pair by a minimum, which may correspond to transitions in which the electrons are lifted to the $N_{\mathrm{VII}}$ and $N_{\mathrm{VI}}$ levels.