The influence of specimen thickness in quantitative electron energy loss spectroscopy: II

Abstract

In a previous paper it was shown that the influence of specimen thickness on quantitative electron energy loss spectroscopy (EELS) can be judged by measuring the intensity ratio of any two characteristic EEL edges as a function of thickness. If the specimen is homogeneous and thickness effects are neglegible then, one can show from Egerton’s formulation that this intensity ratio should be a constant. Any departure from a constant value indicates a breakdown of the quantitative theory due to thickness related effects. It was shown that if the ratio of Ip/IO (Ip = intensity of plasmon loss, IO = intensity of zero loss) exceeds ∼ 0.3 then quantitative analysis can be in significant error. In subsequent work Egerton showed that a better measure is the ratio of ℓn(It/IO) which is related to the ratio of t/λ. Here It is the total energy loss intensity, t the specimen thickness and λ the mean-free path for total inelastic scattering.