Measurement of L XRF cross sections for elements with 33 <= Z <= 51 and their interpretation in terms of L-i (i=1-3) subshell vacancy decay parameters

作者：Duggal Heena; Sharma Veena; Kainth H S; Kumar Sanjeev; Shahi J S; Mehta D

来源：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms , 2018, 429: 19-26.

DOI：10.1016/j.nimb.2018.05.013

• X-ray fluorescence
• Inner-shell vacancy decay
• Fluorescence yield
• Coster-Kronig yield

The L-i (i = 1-3) subshell integral X-ray fluorescence (XRF) cross sections have been measured for 17 elements with 33 <= Z <= 51 following photoionization by the Mn K X-rays (E-K alpha beta = 5.96 keV). The L-i (i = 1-3) subshell X-rays were measured using a low-energy Ge (LEGe) detector at an emission angle, psi = 125 degrees, where angle-dependent emission effects, if any, are nullified as P-2(cos psi) similar to 0. The XRF cross sections were interpreted in terms of available sets of theoretical L-i (i = 1-3) subshell photoionization cross sections, radiative transition probabilities, and the atomic vacancy decay parameters, namely, fluorescence (omega(i)) and Coster-Kronig (fij) yields. A set of L-1 subshell fluorescence (omega(1)) yields was deduced for the elements with 37 <= Z <= 51 from the present measured L gamma(2,3,(4)) [L-1-N-2,N-3(O-2,O-3)] XRF cross sections. The omega(1) values exhibit jumps at Z = 40 and 49, which are identified to be due to cut-off of the L1L2M4,5 and L1L3M4,5 Coster-Kronig (CK) transitions predicted by calculations based on relativistic Dirac-Hartree-Slater (RDHS) model. However, the measured omega(1) values are found to differ considerably from those based on the RDHS model calculations for the elements below Z = 50. The pronounced discrepancies between measured and theoretical omega(1) values are likely to be due to overestimation of the L-1-L2,3M4,5 CK transition rates by a factor of similar to 2-3. Our experiential results demand consideration of extra-atomic relaxation from the solid-state effects and exchange splitting in many-body theoretical calculations of the low-energy CK transitions.

• 出版日期2018-8-15