Question

7.7 What are two main functions of an ion gun in an AES and XPS system?

7.10 How can you tell Auger peaks from photoelectron peaks in an XPS spectrum?

8.10 Why does ToF SIMS use a pulsed, not continuous, primary ion beam?

Answer 1

Answer 7.7 : Ion gun in an AES (Atomic Emission Spectroscopy) ejects atom ions using high potential difference at filament, where as in XPS ( X-Ray Photoelectron Spectroscopy ) ion beam ejects beam of X-ray photons towards the sample/target.

Answer 7.10 : Auger peaks from photoelectron peaks in an XPS spectrum can be determined by measuring kinetic energy of scattered/reflected photons from the target.

Answer 8.10 : ToF SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) uses a pulsed ion beam because ToF SIMS is used to determine the surface imaging, depth profiling etc. and it is done by removing the surface molecules using injected ions, therefore to remove these these surface molecules and atoms, incident ions should be pulsed or discrete, otherwise whole surface will be destroyed by continuous beam.  

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