First 257 words of the document:
Used to measure the relative atomic masses of atoms/molecular mass of organic
Molecular ions will break up, and some of their bonds break as being ionised. This is called
FRAGMENTATION. Each of these give off a different peaks.
However there are normally a few ionised molecules remaining intact to give a peak
corresponding to the Mr.
HIGH RESOLUTION MASS SPECTROMETRY
Can measure masses to ¾ decimal places.
Often used by organic chemists to help them identify compounds.
A pair of atoms joined by a chemical bond is always vibrating.
Stronger bonds vibrate faster (higher frequency), heavier atoms make the bond vibrate
more slowly (lower frequency)
The frequencies are within infra-red electromagnetic spectrum.
The bonds absorb the infra-red radiation that is the same as the natural frequency of the
bond (corresponds to each other).
INFRA RED SPECTROMETER
1. A beam of heat (infra red) passes through the species.
2. The radiation that emerges is missing frequencies that correspond to the types of bonds
found in the sample.
3. Instrument then plots a graph of the intensity of the radiation emerging from the sample,
called the TRANSMITTANCE, against the frequency of radiation.
4. The frequency is expressed as a wave number, measured in cm1.
THE FINGER PRINT REGION
Infra-red spectrum usually has many peaks.
Each spectrum is as unique as a fingerprint.
Can also identify impurities.