Enhanced resolution in Mössbauer spectroscopy

Abstract

Using a resonant detector in Mössbauer spectroscopy can result in a spectral linewidth that is 1.46 , where is the linewidth of the excited-state nuclear level. As is well known, the minimum linewidth obtained in conventional Mössbauer experiments is 2 . The quantum mechanical calculation using a nuclear resonant detector, which predicts this result, is presented. The fundamental equations describing the system are solved by means of perturbation theory in the frequency domain. The model system is taken to consist of a source nucleus, an absorber nucleus, and the resonant-detector nucleus. As noted, the minimum linewidth obtained in a Mössbauer spectrum taken under these conditions is found to be appreciably smaller than the linewidth obtained in a conventional Mössbauer set-up. Thus the conversion-electron, resonant-detector scheme may be used to advantage in experiments requiring the highest possible energy resolution.

Mössbauer and X-ray Diffraction Spectroscopy of High-Iron Bauxites from Kazakhstan

“…57 Co in a chromium matrix with an activity of 25 mCi (Cyclotron Co. Ltd., Obninsk, Russia) was used as a source of γ-quanta; a resonant scintillation detector was used for the registration of Mössbauer spectra. The use of resonant detectors is one of the ways to increase the productivity of the Mössbauer measurements [25][26][27][28] and has a number of advantages, such as improved resolution and increased peak intensity. The resonant detectors reduce the width of the experimentally observed spectral line to 1.43-1.46 Γ [26][27][28], where Γ is the line width of the excited-state nuclear level.…”

“…The use of resonant detectors is one of the ways to increase the productivity of the Mössbauer measurements [25][26][27][28] and has a number of advantages, such as improved resolution and increased peak intensity. The resonant detectors reduce the width of the experimentally observed spectral line to 1.43-1.46 Γ [26][27][28], where Γ is the line width of the excited-state nuclear level. It should be noted that, in the case of resonant detector applications, the shape of the spectrum line differs from the Lorentzian one [26,28].…”

“…Thus, the thickness of the samples was 20 mg Fe/cm 2 . Under conditions where the absorber thickness exceeds the thinness limit, line broadening will naturally occur, but the advantage of relatively narrower lines, compared to a conventional set-up, will remain [27]. The spectrum's measurement time varied from 20 to 80 h. The instrumental error when estimating the values of hyperfine structure parameters did not exceed ±0.04 mm/s.…”