Electron Diff

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

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

Methods Electron beam Lenses for focus of beam Photographic screen

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

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