ABSTRACT
Introduction. The intention of the author was to check the behaviour of the selenium La Xray line in compounds or mixtures containing both magnesium and selenium. The effect of strong dumping of the yttrium La line by the K absorption edge of silicon in the p-sialon ceramics has been presented by Zelechower and Sopicka-Lizer [1], and a similar effect for some elemental couples was predicted. The elemental couples expected to show this effect are presented in the table below together with some spectral parameters [2] (bold lines correspond to the couples measured by the author).______________________________________
Elemental couple
First element K-absorption
edge Eabs [keV]
Second element La (Ma) line energy
Eum) [keV]
Difference (EL(M)"Eabs)
[keV]
Difference (El(M)-Ek<x)
[keV] Na-Eu 1.071 1.131 0.060 0.090 Mg-Se 1.303 1.379 0.076 0.126 Mg-Er 1.303 1.405 0.102 0.152 Si-Y 1.840 1.922 0.082 0.183 Si-Os 1.840 1.914 0.074 0.175 P-Hg 2.143 2.195 0.052 0.182 S-Ru 2.470 2.558 0.088 0.251
Experimental. In order to check the behaviour of the selenium La line in the presence of magnesium, the mixture of two powdered compounds (chromium selenide Cr2Se3 and magnesium acetate Mg(CH3C00)2-4H20) was prepared in the form of a collodion-based suspension. It was then dried and coated with a thin film of carbon in order to dissipate the electrical charge formed during SEM observations and EPMA (EDS and WDS) analysis. Accelerating voltages of 15 kV and 25 kV were applied; the first one for WDS analysis, and the higher voltage for EDS analysis in order to excite not only the selenium La line (1.379 keV) but also the selenium K« radiation (11.21 keV) at an appropriate overvoltage ratio.
