Mass Spectrometer

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  • Created by: Aimee
  • Created on: 28-12-12 20:03
Why is the instrument kept under a vacuum?
So that ions do not collide with air molecules which might stop them from reaching the detector.
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Ionisation
Beam of 'high energy' electrons from an electron gun knocks off electrons from the atoms to form positively charged ions.
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Acceleration
Positive ions attracted towards negatively charged plate and accelerated at a high speed. Lighter ions will travel faster than heavier ions.
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What happens when ions pass through slits in the plates?
They form into a beam.
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Deflection
Beam of ions moves into magnetic field at 90 degrees to direction of travel. Ions deflected by magnetic field depending on their mass to charge ratio. Rate of deflection depends on how heavy the ions are, and magnetic field strength.
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Detection
Ions strike detector, accept electrons, lose charge, and create a current proportional to the abundance of each ion.
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Other cards in this set

Card 2

Front

Ionisation

Back

Beam of 'high energy' electrons from an electron gun knocks off electrons from the atoms to form positively charged ions.

Card 3

Front

Acceleration

Back

Preview of the front of card 3

Card 4

Front

What happens when ions pass through slits in the plates?

Back

Preview of the front of card 4

Card 5

Front

Deflection

Back

Preview of the front of card 5
View more cards

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