Chemical Ideas 6.5
Mass spectrometry is used to measure the atomic or molecular mass of different particles, as well as their relative abundance. It takes place in a (time of flight) mass spectrometer.
The mass spectrometer is a vacuum chamber, allowing the ions to travel from one end to the other without any hindrance by collisions with air molecules.
There are five key parts to the mass spectrometer: the sample inlet, ionisation area, acceleration area, drift region and the ion detector.
Sample Inlet, where:
- gases or liquids are injected into the ionisation area
- solids are heated to vaporise sample
Ionisation Area, where:
- heated filament produces high-energy electrons
- high-energy electrons bombard atoms or molecules in the sample (electron impact)
- sample is ionised, forming CATIONS
- X (g) + e- --> X+ (g) + 2e-
- fragments are formed.
Acceleration Area, where: