Eur. Phys. J. D (2016) 70: 84
https://doi.org/10.1140/epjd/e2016-60472-7

Regular Article

Photon induced L₃ vacancy alignment at tuned photon energies

¹ Nuclear Science Laboratories, Physics Department, Punjabi University, 147002 Patiala, India
² X-ray Optics Section, Indus Synchrotron Utilization Division, Raja Ramana Center for Advanced Technology, 452013 Indore, India

^a e-mail: rmsingla@yahoo.com

Received: 14 August 2015
Received in final form: 18 December 2015
Published online: 14 April 2016

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 E₁ excitation with available theoretical/empirical/experimental values that required additional measurements for source, geometry and efficiency factor S₀GεL_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 A₂ values are very much within the limits, 0.05 <A₂< 0.5, except for Lu, Ta and Pb at E₂ excitation and for W, Pt and Hg at E₁ excitation where values are <0.05. At E₃ excitation, the vacancies only in L₃ are aligned (A₂ ≦ 0.2) in all the cases. The pattern of A′₂ (Coster-Kronig corrected A₂) 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.