X-ray Analysis SEM versus AEM

There are three problems with microanalysis of thin films in the AEM  

Spurious x-rays may be produced that can be detected and confused with x-rays from the specimen—this can be limited by the use of a beryllium or graphite sample holder. 

Beam currents in the AEM are small (compared to the EPMA). This and the very 

A thin film specimen must be prepared that is representative of the bulk and has a reasonably uniform thickness. 

Generally, there are small amounts of heavy elements in a polymer, and these low levels are difficult to detect unless they are concentrated. Leaving the sample for long periods of time to build up the signal may not work as the material may be unstable in the electron beam. Because changes may occur in the sample under study, quantitative analysis of heavy elements in polymers in either the SEM or AEM is difficult. 

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