高分解能けい光X線分析法による石炭中の硫黄の状態分析

抄録

Chemical states, especially oxidation states, are knowm to have various effects on x-ray spectra from sulfur. The efiects, however, are not large and it is rather difficult to observe them with a conventional commercially available x-ray spectrometer. A high resolution two-crystal x-ray spectrometer recently constructed was used for the observation of these phenomena in order to utilize them for the chemical state analysis of sulfur in coal.
Pressed samples were excited with x-rays from a Cr target tube. Resultant fluorescent x-rays (SK_α) were analyzed with the two-crystal spectrometer (prototype of Toshiba AFV 701) equipped with Ge (111) or ADP (101) crystals. A gas flow proportional counter was used as a detector. Pulses from the detector were stored in a multichannel pulse height analyzer (multiscaler mode. In case of a low intensity, the spectrometer was scanned repeatedly and pulses were accumulated several times.
The energy of SK_α increases with the increase of oxidation number. The spectrum from Na₂S₂O₃, which contains S^2- and S⁶⁺, shows two components which correspond to S_2- in FeS and S⁶⁺ in Na₂SO₄. This fact means that qualitative and quantitative chemical state analyses can be performed by measuring SKα spectra precisely.
SKα from coal has a strong peak and a weak shoulder which is on the short wavelength side of the intense main peak. These two components were concluded to be due to S^2- and S⁶⁺ by comparing their positions with the spectra of known compounds.
Ouantitatne analyses of S^2- and S⁶⁺. were performed with a non-linear least square method. The result for variaus coals were discussed (total S: 0.6-3. 3%, S⁶⁺: 5-28).