Discussion about the effects of Mössbauer source line broadening

A detailed analysis of the effects of Mössbauer source line broadening is provided. Computer calculations of emission line broadening of Mössbauer sources with various effective thicknesses using the quantum mechanical theory of the emission spectrum proposed by Odeurs and Hoy, Nucl. Instrum. Methods Phys. Res. B, 254 (2007) 143-148 [1] are made. Corresponding calculations are performed using two simpler classical models giving an account of the non-resonant absorption of the radiation. Differences between the results obtained with the theory of Odeurs and Hoy, other model calculations and experimental data, and also inaccuracies, which could give rise to unusual large broadenings, are discussed. Two experimental tests are described, which unambiguously show that the broadenings calculated in [1] as a result of source line self-absorption broadening (age broadening) are huge and unrealistic. These quantitative evaluations of the age broadening yields an increase of line width of about 0.0004 mm/s for the decrease of ⁵⁷Co/⁵⁷Fe source activity by 1 mCi. Our conclusion is that the predicted observation of "hole burning" line profile could be possible, but only at huge source activities and thicknesses, which are practically not used.