Zusammenfassung der Ressource
Mass Spectrometry
- Uses
- Relative atomic mass
- Relative molecular mass
- relative isotopic abundance
- Molecular structure
- Step 1- Vaporisation
- The sample is vaporised
by an electrical heater
- Step 2- Ionisation
- The gas particles are bombarded with high
energy electrons to ionise them by knocking
off electrons, leaving positive ions.
- Step 3- Acceleration
- The positive ions are accelerated by an electric field
- Step 4- Deflection
- The positive ions' paths are altered with a magnetic field. Lighter ions have less
momentum so are deflected more than heavier ions. For a given magnetic field,
only ions with a particular mass/charge ratio make it to the detector.
- Step 5- Detection
- The magnetic field strength is slowly increased. As
this happens, different ions can reach the detector. As
they hit the detector they release a current.The bigger
the current the more of that isotope is present in the
sample. A mass spectrum is produced.