infrared spectroscopy

• absorption of infrared radiation causes covalent bonds to vibrate more and absorb energy and bend
• ionic bonds don't absorb radiation, only covalent bonds
• fingerprint region:

  • many peaks which are difficult to assign
  • region below 1500cm-1
  • unique part of spectrum of a molecule
  • can be used to identify the molecule by comparison with a database
• infrared can be stopped by greenhouses gases. it enters as short wavelength and can't leave.
• what are the uses of infrared radiation?

  1. identify air pollutants
  2. breathalyser
• identifying air pollutants:

  • identify functional groups in pollutants
  • each pollutant will have a different spectrum
  • measuring concentration or abundance of the pollutants
• breathalyser: contains an IR spectrometer which measures the ethanol in breath