Standard performance criteria for analytical electron microscopy

Users of analytical electron microscopy lack easy‐to‐use standards for assessing the consistency and quality of analytical performance. We propose using a Cr thin film of known thickness to measure three important characteristics related to performance: the Cr Kα peak‐to‐background (P/B) ratio, the X‐ray spectrometer relative efficiency, and the spectrometer energy resolution. We used a Cr specimen to determine the instrumental factors which influence the P/B ratio, finding that the highest P/B ratios are achieved in scanning transmission mode at the highest available accelerating voltage. We present values of the P/B ratio, and the detector relative efficiency and energy resolution which can be used for comparison in other laboratories using the standard film. 1994 Blackwell Science Ltd