Widths of the L x-ray lines of the rare-earth elements

An improved version of a single-crystal high-angle goniometer and a NaI scintillation detector were used to measure the widths of the $L{\alpha }_{1.2}$, L β₁₋₄, and L γ₁ x-ray lines of the elements 58≤Z≤74 and the widths of the less prominent lines L β₁₅, Ll, Lη, and Lγ₁′ of several elements in the same group. The x-ray spectrum of these elements was produced by bombarding them with an electron beam of constant energy and flux, and a computer program was used to unfold the physical widths of their emission lines. These results, as well as the previously reported values of linewidths of the higher-Z elements, are compared with the most recent theoretical predictions.