Electron 
                       Electron 
                Microscopy
                Microscopy
                    Timothy G. Standish, Ph. D.
                                                                   ©2001 Timothy G. Standish
              History and Applications
              History and Applications
   Electron microscopes were developed around the 
      same time as the development of television sets and 
      utilize much of the same technology
   They take advantage of the short wavelength of 
      electrons. As the wavelength is shorter, higher 
      resolution is possible than with regular light 
      microscopes
   Scanning Electron Microscopes (SEM) are 
      analogous to dissecting microscopes
   Transmission Electron Microscopes (TEM) are 
      similar in principle to compound microscopes
                                                                   ©2001 Timothy G. Standish
                   A Television Monitor
                   A Television Monitor
                                            Electron beam
                                                 Magnets-
                                                            Electron Gun
                                    Vacuum
                                 + Phosphore coated screen
                                                                   ©2001 Timothy G. Standish
        Scanning Electron Microscopy
        Scanning Electron Microscopy
    SEM is very good for looking at surfaces
    SEM gives almost infinite depth of field
    SEM cannot show color
    With the right detectors SEM can be used to 
       determine the elements in a sample
    SEM can go to high magnifications, but 
       cannot achieve magnifications as high as 
       those achieved with Transmission Electron 
       Microscopy
                                                                   ©2001 Timothy G. Standish
        Scanning Electron Microscope
        Scanning Electron Microscope
  -
   +                                                                  …..
                                                                   ©2001 Timothy G. Standish