Stage 1 Ionisation electron impact ionisation

Question 1

There are two key ways in which the sample could be ionised:

Answer 1

Electron Impact (or electron ionisation)

Electrospray Ionisation

Question 2

Electron Impact Ionisation

This method of ionisation is used for elements and substances which

and why

Answer 2

have a lower molecular mass

would causer larger molcules to fragment

Question 3

Electron Impact Ionisation first step

Answer 3

The sample is vaporised and then bombarded with high energy electrons

The electrons are ‘fired’ from an electron gun

The electron gun is a hot wire filament which emits electrons as a current runs through it

Question 4

second stage As the sample is bombarded by these electrons, an …. is knocked off each particle, forming a … ion

Answer 4

electron

1+

X (g) → X+ (g) + e-

Question 5

third stage of Electron Impact Ionisation The 1+ ions which have been formed are called and what are they attracted to

Answer 5

molecular ions, or M+ ions
These are then attracted towards a negatively charged plate

Question 6

forth stage what happens after they are attracted to the negative charged plate

Answer 6

This accelerates them through the mass spectrometer

The molecular ion can be broken down further, or fragmented

The fragments are also accelerated through the sample and hit the detector, causing different peaks to show on the mass spectrum which is produced