Spectroscopy

Spectroscopy

Spectroscopy is the technique of splitting light (or more precisely electromagnetic radiation) into its constituent wavelengths (a spectrum), in much the same way as a prism splits light into a rainbow of colours. However, in general, a spectrum is generally more than a simple ‘rainbow’ of colours. The energy levels of electrons in atoms and molecules are quantised, and the absorption and emission of electromagnetic radiation only occurs at specific wavelengths. Consequently, spectra are not smooth but punctuated by ‘lines’ of absorption or emission.

Old style spectroscopy was carried out using a prism and photographic plates. These days, modern spectroscopy uses diffraction gratings to disperse the light, which is then projected onto CCDs (Charge Coupled Devices) similar to those used in digital cameras.