L X-ray fluorescence cross-sections of some elements in the atomic number range 50 ≤ Z ≤ 59 have been calculated theoretically according to subshell excitation energies of elements. The Coster-Kronig transitions (f₁₂, f₂₃, and f₁₃) are non-radiative transitions. The Coster-Kronig enhancement factors due to the effect of the Coster-Kronig transitions on L X-ray fluorescence cross-sections have been calculated theoretically. The calculated values have been compared with other earlier experimental and theoretical values.
Chemical Effects on the K_{β}/K_{α} X-ray Intensity Ratios for Some First-row Transition Element Compounds Were Studied Experimentally and Calculated. the Vacancies in the K Shell Were Created by 59.5 keV γ rays from an ^{241}Am Radioactive Source and Characteristic X-ray Radiation from Sample Was Measured by Using Si(li) and Ge(li) Detectors. the Calculations Were Carried Out Using Brunner's Model. the Calculated Relative K_{β}/K_{α} X-ray Intensity Ratios Are in Good Agreement with the Present and the Previously Published Experimental Data.