Alfred O.C. Nier 1911-1994 Electron Impact (Nier-type) Thermal - PowerPoint PPT Presentation

Alfred O.C. Nier 1911-1994

Electron Impact (Nier-type)

Thermal Ionization

Plasma Ion Source

Microwave Plasma source

Secondary Ionization

Sputter Ionization Source

Matrix-assisted Laser Desorption and Ionization (MALDI)

Electrospray Ionization

Relative pros and cons of different ionization techniques Ionization type Efficiency Selectivity Fragmentation Stability Electron impact + + + + Thermal ionization + - - ++ RF Plasma - +++ ++ - Sputter +++ ++ + - MALDI ++ -- - + Electrospray - - -- - Resonant +++ --- - + photoionization

Electron Energy

Open versus Tight sources

Pushing versus Pulling

Electrostatic lens