Energy Dispersive Microanalysis is the measurement of X-ray energies emitted during electron bombardment of a sample in a transmission or scanning electron microscope.

By determining the energies of the X-rays emitted, the elements within the sample can be identified (qualitative analysis).  The rate of detection of the X-rays is used to measure the amount of each element present (quantitative analysis).  If the electron beam is rastered over an area of a sample then an X-ray map showing spatial variation of elements in the sample can be acquired.

An EDX system comprises a number of key components:

• An Energy Dispersive detector to detect the X-rays
• A Pulse Processor to interpret the energies emitted
• A software interface to run the system including the acquisition and analysis of results

EDX is used by scientists for various applications, including quality control, materials research and characterization, and failure analysis.

SPECTRUM IMAGING

A full X-ray spectrum for every pixel is acquired and stored and can be used to analyse the chemistry of the sample after acquisition.  A Secondary or Backscattered Electron ‘survey image’ is also acquired concurrently for spatial registration.  This resultant data set (or data ‘cube’) becomes almost like a ‘virtual’ sample.

X-ray Maps and Linescans can be acquired from Spectrum Images via post processing.  Quantitative Analysis can also be preformed on areas of the data set of interest. 

X-ray maps must be dead time corrected, so any changes in count rate due to variation of the sample thickness or beam intensity are correctly represented. 

Spectrum Imaging is beneficial to scientists as it allows them to analyse a sample with minimal knowledge of its composition beforehand.  This is because all X-ray data is collected.  There is no need to define specific energy windows for X-ray mapping before collecting the data as this can be done after acquisition.

 

 

 

Copyright © 2010 Thomson Scientific Instruments Pty Ltd
Last modified: 16 May 2010