A simple formula for the thickness correction of symmetrical Moessbauer doublets. Application to spin cross-over systems

We have calculated the Moessbauer absorption integral for symmetrical quadrupole doublets as a function of the effective thickness T of the sample and of the ratio QS/Γ (quadrupole splitting/natural width); the resulting absorption A can be well approximated by a simple expression A∝T/(1+αT), where α is a function of the resolution QS/Γ of the absorption lines. A convenient analytical expression is given for α(QS/Γ). As an example, the thermal variation of the absorption area of a spin cross-over system is analysed. (orig.)