Studies on chemical effects on x-ray intensity ratios of Kβ/Kα in nuclear decay of technetium nuclides 99mTc, 97mTc, and 95mTc

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Abstract
Chemical effects of characteristic x-ray intensity ratios of Kβ/Kα were investigated for the second d-group element Tc in the decay processes 99mTc → 99Tc (two-step isomeric transition), 97mTc → 97Tc (one-step isomeric transition), and 95mTc → 95Mo (electron capture). The objective nuclides were produced by (n, γ)β−, (d, xn), and (α, xn) reactions and were chemically separated from the target materials. The x rays were measured with a pure germanium detector, and the Kβ x rays were analyzed into the two components K′β1 and Kβ2 using a computer program. The chemical effect of the intensity ratio was more pronounced for K′β2/Kα than for Kβ1/Kα, as expected. The effect was larger in KTcO4 than in the other species of Tc2S7, K2TcCl6, and Tc metal. The effect in the two-step isomeric transition in 99mTc was found to be larger than in the one-step isomeric transition in 97mTc. The effect in the electron capture in 95mTc (Mo x rays) was similar to that in 97mTc although the ratio Kβ/Kα was smaller in 95mTc than in 97mTc, reflecting the change of nuclear charge. The tendency of the observed chemical effect was explained by taking into account the interfering factors which involve Pauling’s ionicity in chemical bonding between Tc and its counter atom.