week 4.2

Question 1

Wave-particle duality

Answer 1

that any matter exhibits both wave
and particle properties at all times

Question 1

how does EI work?

Answer 1

Energised electron beam formed though thermionic emission by heating a
tungsten wire filament.
Electrons in the beam are energised to 70eV.
Electrons attracted across the ion source to the anode (positive electron trap).
Off-axis magnet makes electron beam spiral to increase the interactions
between the electrons and vaporised analyte and thus improve ionisation
efficiency.

Question 2

why is 70 ev selected for ionisation?

Answer 2

At 70eV the de Broglie
wavelength of electrons is
0.15nm which similar to typical
C-C bond length.
Maximises the chance of energy
transfer from electrons to C-C
bonds of analyte.
Increases chance of ionisation.

Question 3

what is CI?

Answer 3

Proton transfer from methanium ion

The ions have less residual energy after ionisation and so there is less
fragmentation

Question 4

what can CI and EI be used for?

Answer 4

EI
Thermally stable, non-labile,
volatile.

CI
Thermally stable, volatile.