In scanning electron microscopy a sample is scanned with a nanoscopic electron beam. The interaction of matter with the electrons will cause  emission of several different signals, each providing a specific type of information. Low energy secondary electrons primarily show a topographic contrast, while more energetic backscattered electrons result in a contrast based on the local mass density. In addition to emitted electrons also element specific X-rays are generated providing information on the local elemental composition.

Operated under high vacuum conditions the FEI Quanta 250 ESEM with its Schottky field emission gun source can obtain a image resolution down to 1 nm (SE at 30 kV). In addition it can also operate under low vacuum or even environmental conditions. This makes it possible to analyze wet (biological) samples and non-conductive samples without the need for sputtering/coating. The FEI Quanta line includes six variable-pressure and environmental scanning electron microscopes (ESEM™). All of which can accommodate multiple sample and imaging requirements for industrial process control labs, materials science labs and life science labs. 

Operation modes:

  •  high vacuum
  •  low vacuum
  • ESEM


  • Everhardt-Thornley secondary electron detector (SE)
  • Backscattered Si detector (BSE)
  • Large Field Gaseous SE detector (LFD)
  • Gaseous SE detector (GSED) for ESEM mode
  • Energy Dispersive X-ray (EDX) detector
  • Wavelength Dispersive X-ray (WDX) detector