Electromagnetic radiation . . .
A simple introduction to the electromagnetic spectrum, and the place of ultra-violet and visible light in it.
A double beam absorption spectrometer . . .
Explains how a UV-visible absorption spectrum is obtained using a double-beam spectrometer
Bonding theory for UV-visible absorption spectra . . .
An introduction to two essential bits of bonding theory (anti-bonding orbitals and conjugated bonds) that you need in order to understand the absorption of light by organic compounds. You won't make full sense of the next page below without reading this first.
What causes molecules to absorb UV and visible light . . .
Takes a reasonably simple look at the theory behind absorption in the UV-visible region. You should read the page about bonding (above) first to really understand this one.
The Beer-Lambert Law . . .
A brief look at the Beer-Lambert Law and an explanation of the terms absorbance and molar absorptivity (molar absorption coefficient).
Using UV-visible absorption spectroscopy . . .
Explains how this is used in identifying functional groups in organic molecules, and in measuring concentrations.