LX-Ray Transition Probabilities in Elements withZ>~57

The $\frac{L{\beta }_3}{L{\beta }_4}$, $\frac{L{\gamma }_1}{L{\beta }_1}$, $\frac{L{\alpha }_2}{L{\alpha }_1}$, $\frac{L{\beta }_{2,15}}{L{\alpha }_1}$ and the $\frac{L{\beta }_{2,15}}{L{\alpha }_2}$ transition probabilities have been measured for some 27 elements ranging in atomic number from ${}_{57}{}^{}{}_{}{}^{}\mathrm{La}$ to ${}_{92}{}^{}{}_{}{}^{}\mathrm{U}$. Other $L$ transitions have also been measured for a smaller number of elements in the same range of atomic numbers. This has been accomplished by bombarding these elements with a constant energy electron beam and measuring their x-ray emission spectrum. The measured ratios are compared with the most recent calculation based on a relativistic Hartree-Fock-Slater (RHFS) potential, and screened Coulomb potential. In general, the form of the dependence of these ratios on atomic number predicted by calculations based on a RHFS potential is favored and the agreement between theory and experiment ranges from excellent for the $\frac{L{\alpha }_2}{L{\alpha }_1}$ ratio to a discrepancy of about 22% in the $\frac{L{\beta }_{2,15}}{L{\alpha }_1}$ ratio for elements of large atomic number.