The Electron Microscopy Center

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Energy Dispersive x-ray spectroscopy (EDS)

Description

When a high energy beam interacts with matter x-rays are produced. An x-ray spectrometer can detect and count this providing information on the elemental content where the electron beam is focused. On the S-4300 SEM, S-3200 SEM and the 2010F STEM, this beam can be computer controlled and elemental profiles and maps can be produced. Spot analyses and Multipoint data can be obtained on the S-4300 SEM and the S-3200 SEM. Spot analyses can also be performed on the 2000FX TEM.

Specifications

  • SEM resolution is about one micron to 10 nm.
  • STEM resolution is about 1 nm.
  • Sensitivity is about 1 percent for both SEM and STEM

Instrumentation

  • S-3200 SEM with EVeX-EDS system (detects elements down to and including Boron)
  • S-4300 SEM with PGT-EDS system (detects elements down to and including Carbon)
  • JEOL 2010F STEM with Oxford EDS system with Es Vision (detects elements down to and including Carbon)
  • JEOL 2000FX TEM with Oxford EDS system (detects elements down to and including Carbon)

Advantages

  • Straight forward interpretation with automated semi-quatitative analysis

Limitation

Sensitivity of approximately one percent
Semi-quantitave analysis accuracy of approximately 10 percent
For elements lighter than Na sensitivity rapidly decreases.
Mapping can take hours, especially when there are elements with a low percentage concentration

Examples

Example EDS spectrum

Example semi-quantitative EDS map of bi-metallic catalyst obtained on JEOL 2010F.
Map acquired in approx 30 minutes, 150 pixels by 100 pixels.
Optimized EDS mapping developed by Alan Dozier supported by NanoTEM Corp.