Zeiss SIGMA VP-FESEM

    Equipment/facility: Equipment

      Description

      This is a variable pressure field emission scanning electron microscope, which allows users to perform high resolution SEM work for conventional secondary electron imaging, backscattered electron imaging, cryo-SEM, EDS elemental analysis, and 3View reconstruction

      Details
      The scanning electron microscope is an instrument which uses a lens system to focus electrons generated from an electron gun to a fine point at the surface of a conductive sample.

      The focused beam interacts with the specimen reflecting electrons which may be absorbed by the sample and subsequently give rise to light (cathode luminescence), electric current, low energy secondary electrons, backscatter electrons, and x-rays.

      The most useful for imaging include the secondary electrons which are generated at the points where the beam interacts with the sample and subsequently attracted to a detector composed of grid held at a low 50eV positive potential, a scintillator and photomultiplier tube. The number of secondary electrons are dependent upon atomic identity, topography and sample orientation at the point of impact.

      The electron beam is deflected along a straight line on the sample and terminated at the end of the area set by the magnification selected. It is then returned to the starting point, moved down a short distance and repeated along a line parallel to the first until an area rectangular in shape is scanned. The series of lines constituting the scanned area is referred to as a raster. Deflector coils on the CRT are in synchronization with the scanning coils affecting the SEM beam but the raster on the CRT is kept constant while the area scanned on the sample can be changed. The ratio of the linear size of the two rasters is the magnification.

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      electrons
      magnification
      scanning electron microscopy
      scanning
      coils
      electron microscopes
      deflectors
      electron guns
      photomultiplier tubes
      electric current
      pressure distribution
      scintillation counters
      field emission
      synchronism
      topography
      cathodes
      grids
      lenses
      electron beams
      luminescence