Photon induced L3 vacancy alignment at tuned photon energies

Abstract

Photon induced L3 X-ray measurements for L α /L l cross-section ratios in elements, 66 ⩽ Z ⩽ 83, at tuned photon energies on synchrotron Beamline-16 at Indus-2, India have been used to study the effect of Coster-Kronig (CK) transitions and photon energies on alignment of L3 vacancies. Certainty and reliability of the measurements were checked from comparison of measured L α and L l fluorescence cross-sections at E 1 excitation with available theoretical/empirical/experimental values that required additional measurements for source, geometry and efficiency factor S 0 GeL α/l in the used set-up. Fall/rise trend of the ratios with energy for different Z’s was found to resemble the off/on-set pattern of CK transitions as pointed out by Bambynek et al. and Campbell. Evaluated alignment parameter A 2 values are very much within the limits, 0.05 <A 2< 0.5, except for Lu, Ta and Pb at E 2 excitation and for W, Pt and Hg at E 1 excitation where values are <0.05. At E 3 excitation, the vacancies only in L3 are aligned (A 2 ≦ 0.2) in all the cases. The pattern of A′ 2 (Coster-Kronig corrected A 2) variation with energy for Dy, W, Pt, Hg and Bi resembles our previously reported theoretical patterns that lends mutual support for both current measurements and earlier theoretical results.