1. Electron Diff

2. Electron Diff. Based on wave nature of matter
Beam of electrons striking atomic nuclei
1A low energy caused by int. with outer e- and nuclei
Less than 1A beam is used in diff. as greater absorption by matter
Produces concentric rings on plate : Dark – max scattering and Lighter – min scat.
poorly resolved
Scattering by inelastic or incoherent

3. Advantages Easily to get Higher electron beams available – short time
Length can be altered by voltage
Sensitive to electric and magnetic fields

4. Methods
Electron beam
Lenses for focus of beam
Photographic screen

5. Process 50 K volt beam on thin film at low psi
E- int. strongly with molecules
Emerging beam falls on p plate
Concentric rings formed

6. Applications Investigation of surfaces Study of diff. of e- at low psi
Evaluation of bond lengths and angles
Det. Of molecular config.