Slide 6 of 25
Notes:
Specimen in the EM column is desiccated, suffocated, electrocuted, cooked and nuked. Thus there should be specific precautions in sample preparation for electron microscopic observation. Specifically for biological samples - that mostly consist of the very light atoms of hydrogen, oxygen, carbon, phosphorus and sulfur - electrons will easily penetrate the tissue without scattering or deflection and thus the contrast of the image will be very low.
In contrast to LM, color does not exist in TEM. The reason for that is the single wave length (the length depends on the accelerating voltage) of the electron beam - in contrast to the spectrum that combined gives the white light. The single wave illumination in the EM is beyond sensitivity&127; of the human eye, thus it should be converted into smth detectable. This is done by using the viewing screen covered with phosphorescent material: electrons hit the screen, and pass their kinetic energy to the phosphorus molecules that emit green or yellow light detectable by the eye.
