T V Krishnan
Articles written in Proceedings – Section A
Volume 60 Issue 2 August 1964 pp 75-84
Field theoretical effects in X-ray spectra
The L_{I}-L_{II} screening doublet separation in the relativistic approximation up to Z^{20} has been compared with that obtained experimentally by the transitions M_{IV}L_{II} (L
Volume 65 Issue 1 January 1967 pp 45-48
Thickness effect in the X-ray K absorption edge of nickel
Effect of absorber thickness on the X-ray K absorption edge of nickel has been recorded photographically. The extended structures show a variation in their relative intensities. In agreement with the earlier observations of Parratt and Sawada the structures in the immediate neighbourhood of the edge show a decrease in their absorption intensities and the fluctuations following them up to 140 eV. remain unaltered. In addition, it is found that the structures lying beyond 150 eV. from the edge become more pronounced on the increase of absorber thickness.
Volume 70 Issue 4 October 1969 pp 189-200
X-ray K-line intensity ratios
Volume 77 Issue 1 January 1973 pp 26-41
Effect of field theoretical corrections on X-ray spectra
The wavelengths of$$K_{\alpha _1 } , K_{\alpha _2 } , K_{\beta _1 } , K_{\beta _2 } , K_{\beta _2 } I and K_{\beta _2 } II$$ lines of heavy elements of atomic number 70–92 and the associated energy levels, K, L_{II}, L_{III}, M_{II}, M_{III}, N_{II} and N_{III} have been calculated using a modified form of the relativistic energy formula of Sommerfeld, incorporating in it both the total and internal screening constants in a closed form. All the field theoretical corrections in the second and the fourth order as well as the finite nuclear size correction have been included.
The relative intensities$$K_{\alpha _2 } /K_{\alpha _1 } , K_{\beta _2 } / K_{\beta _1 } , and K_{\beta _2 } II/K_{\beta _2 } I$$ have been calculated with relativistic wavefunctions. In addition to the retradation and screening, field theoretical corrections have also been used. A logical extension of the one electron-model with application of the field theoretical corrections improves the calculated results of not only the energy levels but also the relative intensities of X-ray lines.
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