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Electron Microscopy

Electron Microscopy (EM)

Applying Atomic Structure Knowledge to Chemical Analysis

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Electron Microscopy

Electron Microscopes

• achieve higher magnification and resolution than optical scopes.

• use electrons instead of light to image samples.

• use electromagnets (instead of glass lenses) to focus the electron beams.

• require samples to be exposed to the electron beam in a vacuum.

• allow for analysis of a sample’s composition in addition to imaging.

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Electron Microscopy

Electron Microscopes

• Scanning Electron Microscopes:

• Scan (raster) across a sample surface to get a high resolution images.

• used for many different types of samples.

• Transmission Electron Microscopes:

• creates an image after passing electrons through an ultra thin sample that is somewhat optically transparent.

• are used for biological and metrology samples to get high resolution images of cells, crystals, and their structures.

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Electron Microscopy

Electronics and Signal Processing

Video Signals

Computer

E-Beam, Magnet, and

Detector Control Systems

Video Signal

Electro-Optical Column

Sample Chamber

Scanning Electron Microscope Instrument Diagram

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Electron Microscopy

Scanning Electron Microscope

Hitachi S800 SEM at the USF College of Engineering Metrology Laboratory

Image and x-ray analysis and processing

Sample compartment

Electron beam

Control system for e-beam, magnetic

fields, and communications

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Electron Microscopy

SEM Electron Beam

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Electron Microscopy

SEM of a filter paper with 0.45 micron (0.45 x 10-6 meters) pores at 1000x magnification. The white particles are aluminum oxide.

SEM Image of Filter Paper

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Electron Microscopy

SEM of the same filter paper with 0.45 micron (0.45 x 10-6 meters) pores at 10,000x magnification. The white particles are aluminum oxide.

SEM Image of Filter Paper

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Electron Microscopy

Sample SEM Images

SEM of the old USF logo etched on a polymer substrate. Note the micron scale.

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Electron Microscopy

Sample SEM Images

SEM of nickel (white) film test pattern on silicon carbide substrate. Note the 100 micron scale.

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Electron Microscopy

Medical Applications:•compare healthy and unhealthy blood and tissue

samples•study the effects of medication on patients•analysis of crime scene evidence

Structural Applications:•faults and weaknesses of building materials•crystal structure of materials•characterization of size, shape, and distribution of

various particulates (such as air pollution)•adsorption of particles on surfaces

Electron Microscope Applications

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Electron Microscopy