T.O.F Mass Spectrometry

• What must all mass spectrometry happen under?


  A vacuum
• Why is mass spec. kept under a vacuum?


  To prevent the ions produced from colliding with the molecules in the air.
• What are the main stages of TOF Mass Spectrometry?


  Ionisation, Acceleration, Ion Drift, Detection, Data Analysis
• What is the first stage of the ionization process in mass spectrometry?

  Ionisation
• How is the sample prepared for ionisation in mass spectrometry?

  The sample is ionised using different methods.
• What are the two methods of ionisation?

  • Electron impact
  • Electrospray Ionisation
• What is a characteristic of the electron impact method of ionisation?

  It can cause fragmentation of longer molecules.
• What type of sample is required for the electron impact method?

  The sample must be gaseous.
• What is the process of electrospray ionisation?

  The sample is dissolved in a polar, volatile solvent and a high voltage is applied through a needle.
• What happens to the sample after applying a high voltage in electrospray ionisation?

  A fine mist is produced.
• What occurs to the particles in electrospray ionisation?

  The particles gain a proton from the solvent to become an ion.
• What is an example of a reaction in electrospray ionisation?

  Fe(g) + H⁺ → FeH⁺(g)
• What happens to positive ions acceleration?

  They are accelerated towards a negatively charged detection plate.
• What is the effect of acceleration on the kinetic energy of ions?

  It gives the same kinetic energy to all the ions.
• What is the formula for kinetic energy?


  KE = \frac{1}{2}mv^2
• What units are used for kinetic energy in the formula KE = \frac{1}{2}mv^2?

  Joules (J), kilograms (kg), and meters per second (m/s).
• How does the mass of ions affect their arrival at the detector?

  Lighter ions will reach the detector first.
• What is ion drift and its relation to kinetic energy and mass?

  • Ions have the same kinetic energy.
  • Ions with lower mass drift at a higher velocity.
• What happens to ions with lower mass during ion drift?

  They drift at a higher velocity.