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Chemistry - Spectroscopic techniques in chemical analysis

Spectroscopic techniques in chemical analysis

A wide range of spectroscopic techniques are used in modern analysis.
Examples include mass spectroscopy (MS), atomic absorption spectroscopy
(AA), infrared spectroscopy (IR) and nuclear magnetic resonance
spectroscopy (NMR). Each technique makes use of the fact that different
parts of atoms and molecules interact to different extents with different
wavelengths of electromagnetic radiation. NMR makes use of the fact that
radio waves can cause nuclei to rotate whereas IR utilises the fact that
molecules exposed to radiation in the infrared section of the spectrum will
vibrate.

At this level we are mainly interested in spectroscopic techniques that
depend on electrons in atoms and molecules changing energy levels.

Energy in the form of visible, ultraviolet or infrared radiation is
applied to a sample. Either the energy taken in (absorption) or given out
(emission) by the sample is measured in some way to provide qualitative and
/ or quantitative information.

When atoms become excited by heating, they absorb energy as electrons
move to higher energy levels - further from the nucleus. Excited atoms emit
energy as electrons return to lower energy levels - closer to the nucleus.

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