Resolving power of coincidence Mössbauer spectroscopy

Abstract

The narrowing of Mössbauer absorption lines resulting from time filtering effects is analyzed with regard to the possible utility of this technique in improving experimental line resolution. We demonstrate that in the absence of statistical noise, and provided the line shape is Lorentzian of known width and experimentally undistorted, it is always possible to solve for a completely unknown energy level scheme of a thin absorber, independent of whether or not the individual lines comprising the Mössbauer spectrum can be resolved by eye. We solve analytically a simple model to test the utility of time filtering as an aid to the determination of the parameters of Mössbauer spectra, taking into account the effects of statistical noise. Our calculation indicates that only minor improvement in accuracy can be achieved when non-zero coincidence delay times are introduced, and in view of the experimental difficulties involved in coincidence Mössbauer spectroscopy, it appears to us that time filtering methods are unlikely to compete successfully with computer techniques as a useful experimental tool for spectrum analysis. Some comments as to the relevance of the Heisenberg uncertainty principle to line narrowing are appended.