eTraining Introduction

Specimen Preparation

Leica Ultracut UCT

Histology

JEOL JSM-6400 SEM

Hitachi S-4700 FE-SEM

Hitachi FB-2000A FIB

Microanalysis

Veeco Dim 3000 AFM

Fluorescence Microscopes

Support

X-Ray Mapping

Basic Science

X-ray maps (also called dot maps) are a series of two dimensional images, where each image spatially portrays an individual element present in the sample. In this process, the electron beam is scanned across the specimen and X-rays are collected for a predefined time period (often called dwell time and measured in milliseconds) at each pixel. X-ray maps can appear noisy or grainy. This condition can be minimized by increasing the dwell time. Since each image will involve 10's of thousands (or more) of pixels, increasing the dwell time by even a few milliseconds can require up to hours of additional time to complete. The user selects what elements are mapped based on a thorough qualitative analysis. A separate map is developed for each chosen element. For clarity, each element is depicted in a different color, and the intensity of the color map indicates the concentration of that element. Many specimens contain multiple phases, each comprised of the same elements but in different concentrations. The maps provide a direct visualization of different chemical components in the specimen, and can be compiled into a single image map depicting each phase and its composition in separate colors.

Secondary Electron Image

Secondary Electron Image

Aluminum

X-Ray Map of Aluminum

Calcium

X-Ray Map of Calcium

 

X-ray map quality and accuracy is governed by the same limitations observed in EDS analysis, as in some cases where elements will be in low concentrations, and elements with close orbital energies will appear as peak overlaps. Although these problems are difficult to analyze with EDS, they can be mapped accurately using WDS X-ray mapping.

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