Transmisssion Electron Microscope

Question 1

How does a transmission electroscope microscope work:

Answer 1

• Samples are placed under a high vacuum
• High voltage electron beam partially transmitted through sample
• The beam is emitted from a cathode
• Transmitted electrons are amplified
• The electron beam reflects off a phosphor screen or photo plate
• Or similar light sensor that forms an “image”

Question 2

Name forensic applications of TEM:

Answer 2

• Trace amounts of gunshot residue, heavy metals, explosives,
  DNA on prints, paint, glass and soil

Question 3

How did TEM become a premier tool for micro-structural characterization of materials:

Answer 3

• It uses electron diffraction rather than light and this electron optical system can be used to analyzed a number of different materials in minute trace amounts

Question 4

Advantages of TEM:

Answer 4

• With proper training, easy to operate
• Most efficient and versatile tool for characterization of materials
  1 to 100 NM and up
• Electron beam provides wide range of focus on the sample for more
  thorough examination

Question 5

Disadvantages of TEM:

Answer 5

• High maintenance cost and time consuming preparation
• Samples are required to be thin; examination is destructive
• Limits on the amount samples that can be examined