Infra Red Spectrometry Flashcards
Describe infra-red radiation.
4
It has wavelengths ranging from 10-3 to 10-6 which are therefore longer than those of visible light
It is invisible
It is given off by hot objects
It is absorbed by organic compounds
What can special infra-red cameras be used for?
To find people buried in collapsed buildings
Organic compounds absorb infra-red radiation, describe this.
(3)
Infra-red radiation is absorbed by the vibrations of the bonds in the molecules
A C=O bond absorbs infra-red radiation at a particular frequency while an O-H bond absorbs infra-red radiation at a different frequency
Thus, every organic compound has a unique IR spectrum that can serve as a ‘fingerprint’ for it
How does every organic compound have a unique iR spectrum?
Because every bond absorbs infra red radiation at a particular frequency
What absorbs infra-red radiation in organic compounds?
The vibrations of the bonds
What is the principle of infra-red spectrometry?
2
Organic compounds absorb infra-red radiation of certain frequencies.
The combinations of frequencies that are absorbed depend on the bonding within the molecule and ate unique to the particular molecule
What is the principle of infra-red spectrometry?
2
Organic compounds absorb infra-red radiation of certain frequencies.
The combinations of frequencies that are absorbed depend on the bonding within the molecule and ate unique to the particular molecule
What are the processed that occur in an infra-red spectrometer?
(3)
Infra-red radiation is passed through the sample being analysed
Infra-red radiation of certain fixed frequencies is absorbed
An absorption spectrum is obtained, which can be used to identify the compound
What is obtained at the end of the process of infra-red spectrometry?
An absorption spectrum is obtained
What is infra-red spectrometry commonly used for?
2
To identify plastics and illegal drugs
To back-up evidence for prosecutions arising from breathalyser tests in motoring offences
