An Analytical Expression for Fractional Absorption in Mossbauer Spectroscopy

Removing the restriction that the line widths (Gamma(s) and Gamma(a)) of a source and an absorber be equal, we have obtained an exact analytical expression for the fractional intensity of absorbed gamma-rays in Mossbauer spectroscopy. This expression is compact and consists of three terms; the first two are known in the literature for the case Gamma(s) = Gamma(a), and the third term contains a simple sum of higher-order terms arising from Gamma(s) not equal Gamma(a). We provide quantitative analyses and a discussion of the contribution from this third term and its effect on the fractional absorption of a Mossbauer spectral line.