Process of TOF Mass spectroscopy Flashcards
what is the process of TOF
Vaporise
Ionise
Accelerate
Drift
Detection
What happens in the vaporisation stage
The atom is vaporised into a gaseous state
What happens in the ionise stage
The atom is ionised via electro spray ionisation or Electron impact
What happens in electron impact ionisation
A high energy electron is fired at the sample
X(g) -> X+(g) + e-
What happens in electro spray ionisation
Sample dissolved in volatile solvent and sprayed through a fine needle with a high voltage, causing binding of H+
What happens at the acceleration stage
Positive ions are attracted to negatively charged plate and accelerate towards it. Lighter ions achieve faster speed
What happens at the Ion drift stage
Ions pass through hole in negative plate, forming a beam and travel along the tube to the detector
What happens in the detection stage
Positive ions pick up an electron from the detector, causing a current to flow and thus their times are recorded
What happens at the analysis stage
Signal from detector plate generates a mass spectrum to determine element abundances
How is the abundance of a substance at the detection stage identified?
Current produced is proportional to the species abundance
