Substance vaporised, then high energy electrons fired at it, knocking off electrons, typically forming 1+ ions. The 1+ ions are then attracted toward negative electric plate.
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1) Electron Impact symbol equation
X(g) + e- ---> X+(g) + 2e-
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2) Electrospray ionisation - Explain
Dissolved in polar solvent, e.g H2O. High voltage passed through aqueous solution, causing loss of e-. Ionised particles are separated from solvent, leaving gas of positive ions.
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Acceleration - Explain
Cations accelerated using electric field, causing them to all have the same Kinetic Energy.
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Given that all cations then have the same kinetic energy...
The velocities of each particle depends on its mass. I.e Lighter particles have greater velocity, and heavier have smaller velocity.
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Kinetic Energy =
1/2mv^2
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Therefore v=
sqrt(2E/m)
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Flight Tube/Ion Drift - Explain
Cations travel through hole in negatively charged plate into flight tube. ToF is proportional to sqrt(mass). ∴ lighter particles arrive at detector quicker than heavier.
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Detection - Explain
Cations hit negatively charged electric plate, causing cations to be discharged, by gaining an e- from the plate. E- movement is a current. This curren can be measured. Size of current gives measure of number of ions.
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Detection explained as concisely as possible for shorter questions:
Ions hit detector, causing movement of electrons, causing a current. A larger current means more of that isotope there is.
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