Quantification of interfacial parameters in spatially resolved analysis involving ELNES separation

This paper describes the quantitative aspects of the spatially resolved EELS analysis involved with the ELNES separation method [H. Gu, Ultramicroscopy 76 (1999) 159] in the “spatial difference” technique. A chemical thickness and a concentration of an interested boundary or interface can be obtained. Such quantification can be made either in the analyses using frame scans or the “spectrum-line” profiling technique. These parameters, only available after the spectrum separation, are useful information to describe the interfacial properties in addition to an interfacial ELNES. Examples of a grain boundary and an interface are shown from a well-characterized Si3N4 material. The quantification precision is related to the uncertainty in the separation procedure, and it can be estimated. In the case of the EELS profiling, additional information about the effective probe size can also be obtained. An equivalent probe size, which is defined as virtual probe with a uniform brightness, can be calculated from the separated partial profiles. Similar quantification can be applied to EDS analysis of grain boundaries even when the weak signal from segregated elements overlaps with the large matrix signal. In this case, spectrum subtraction to remove the matrix signal would result in an excess spectrum. The excess of segregation will be quantified together with an excess width and a depletion width. This provides an alternative way to quantify the segregation at the interested interface.