CharacteristicLAbsorption of X-rays for Elements of Atomic Numbers 62 to 77

Characteristic L x-ray aborption wave-lengths for nine elements of atomic numbers 62 to 77.—Since the $L$ absorption wave-lengths had been determined for elements of atomic numbers 55 to 60, 74, and 78 to 92, it was of interest to fill in the gaps. Accordingly compounds of samarium (62), gadolinium (64), dysprosium (66), erbium (68), ytterbium (70), tantalum (73), tungsten (74), osmium (76) and iridium (77) were precipitated upon filter paper and placed in the path of x-rays from the tungsten target of a Coolidge tube. In each case the three $L$ absorption bands together with the emission lines of $W$ were photographed, using a calcite crystal which was rotated with a constant angular velocity. The wave-lengths and the frequency numbers divided by the Rydberg constant, $\frac{\nu }{N}$, are tabluated. The energy levels within the atoms corresponding to the different absorption limits computed in terms of $\frac{\nu }{N}$ from the absorption and emission frequencies, are also given. The regular doublet differences $\Delta \left(\frac{\nu }{N}\right)=\frac{({\nu }_{L_2}-{\nu }_{L_1})}{N}=L_2-L_1$ are found to agree well with the values calculated from the Sommerfeld formula.