Determination of probabilities of vacancy transfer from K to L shell using K X-ray intensity ratios

K to L shell vacancy transfer probabilities (η_KL) for 26 elements in the atomic region 23≤Z≤57 were determined by measuring the I_Kβ/I_Kα intensity ratios. The targets were irradiated with γ-photons at 59.543 keV from ²⁴¹Am annular source. The K X-rays from different targets were detected with a high resolution Si(Li) detector. Theoretical values were calculated using the radiative and radiationless transition rates of these elements. The measured values of η_KL are compared with the theoretical values and data of others. The measurement vacancy transfer probabilities are least-square fitted to third-order polynomials to obtain analytical relations that represent these probabilities as a function of atomic number. The measured values of η_KL for V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se and Br are being reported here for the first time.