Scanning Electron Microscopy

More documents

Recommendations

Info

Variable Pressure SEM (2) • This allows analysis of ‘non conducting’ samples as charge is compensated by gas in the chamber. • Use of an SEM in VP mode does lead to some limitations in it’s operation:- • Because the vacuum is lower in a VPSEM chamber, some resolution of the instrument is lost due to scattering of the electron beam by the gas particles in the chamber. • In situ heating and or cooling (with the appropriate sample stage) is possible in VPSEM to allow direct observation of sample changes. • Compositional analysis is still possible. Analytical Workshop 2012
Compositional Analysis – Back Scattered Imaging • As mentioned previously, when the electron beam hits the sample a number of signals are generated. Secondary electrons are used for looking at surface detail (topography). • EM is also a very powerful technique for analysing composition and compositional distribution in a material\sample. B Analytical Workshop 2012 Signals generated in the interaction volume • Back Scattered electrons are produced just below the surface of the sample (B) and are scattered more by heavier elements than by lighter elements. • The backscattered coefficient, η = (Z-1.5)/6 So, as Z increases, so does the degree of backscatter.
Page 1 and 2: Scanning Electron Microscopy Field
Page 3 and 4: Improving Resolution • Firstly, t
Page 5 and 6: Layout of a Generic SEM Gun 1 Apert
Page 7 and 8: Thermionic Gun Filament Wehnelt cyl
Page 9 and 10: Comparison of Sources •W filament
Page 11 and 12: Scanning the Beam\Beam Interactions
Page 13 and 14: Signal Detection • The Everhard -
Page 15: Variable Pressure SEM •Localised
Page 19 and 20: BackScattered Imaging • Back scat
Page 21 and 22: Examples Images Imaged using ET Det
Page 23: Conclusions •Scanning Electron Mi

Scanning Electron Microscopy

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?