Light Atom Sensitivity of Quantitative HREM

Abstract

Introduction: Modern TEM/STEM instruments with field emission gun and various analytical equipment allow the measurement of interfacial properties by a range of modes and techniques without exchanging the specimen. It is therefore useful to think of a criterion to assess the sensitivity of each technique, e.g. for the location of light atoms, by a commonly applicable formula.Sensitivity measures: A “quantitative” TEM experiment is defined here as consisting of a digital comparison (e.g. via data difference or cross correlation) between experimental (E) and simulated (S) microscopy signal. The matching quality R = f(E,S) is to be optimised (minimum for data difference, maximum for cross correlation). The target quantity of the Q-TEM experiment is assumed to be the location or occupancy of a light atomic column in projection surrounded by heavier atoms in the core of an interface making use of dynamical enhancement effects.