Infra red radiation makes some bonds vibrate more
- some molecules abosorb energy from IR radiation. Extra energy:covalent bonds: more vibrations
- Only molecules made of different atoms can absorb IR Radiation, because the bond polarities change as they vibrate - e.g. O2 and N2 don't absorb IR: but CO2, H2O, NO and NH3 do :)
- Gases that do absorb IR: greenhouse gases because they stop some of IR radiation emitted by Earth from escaping into space.
Different molecules absorb different frequencies
- Gas molecules' bonds have certain fixed energy levels. They are called 'quantised levels'. So a bond's energy can only jump from one level to another: like moving up a staircase.
- This means that only frequencies of radiation corresponding to particular amounts of energy: absorbed.
- Different molecules absorb different frequencies of radiation.
How IR spectroscopy works...
- A beam of IR radiation is passed through a sample of a chemical.
- IR radiation: absorbed by the covalent…