Measurements of Li₂SrSiO₄, K₃[Fe(CN)₆], Fe and Mn₂CrO₄ applying a scintillation counter and a Si PIN diode point detector              

Setup

Samples of Li₂SrSiO₄, K₃[Fe(CN)₆], Fe and Mn₂CrO₄ were measured using transmission geometry on a STOE STADI MP diffractometer equipped with pure Cu Kα₁ radiation. Measurements were carried out with a scintillation counter (with and without secondary beam monochromator; 0.2mm slit size) and a Si PIN diode point detector (0.2mm slit size).

Results

A Si PIN diode enables the energy discrimination of the incident radiation, with a FWHM of the energy peak close to 200 eV. Therefore it is possible to clearly separate between Kα and Kβ radiation of Co, Cu, Mo and Ag and also cut off X-ray fluorescence appearing at absorption edges.

Conclusion

Using a secondary beam monochromator for measurements of Fe (or Mn) containing samples with Cu Kα₁ radiation and a scintillation counter reduces the background and increases the signal-to-noise ratio but reduces the overall intensities to ¼.

The Si PIN diode point detector is able to completely cut off the fluorescence of Fe (and/or Mn) and therefore provides data with a signal-to-noise ratio up to two times higher than the scintillation counter with secondary beam monochromator. Due to the lower height divergence caused by the smaller detector size of the PIN diode compared to the scintillator crystal, the resolution is considerably better.

The slightly decreased intensity of the Si PIN diode due to the smaller detector size compared to the scintillation counter is overcompensated by the lower background and the higher quantum efficiency (~98 % vs. ~30 %).

References

[[1]] A. Le Bail, H. Duroy, J. L. Fourquet, Mat. Res. Bull. 1988, 23, 447.

[[1]] L. W.Finger, D. E. Cox, A. P. Jephcoat, J. Appl. Cryst. 1994, 27, 892.

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