Absorption and Emission Spectra
Absorption lines were discovered first by an English chemist called William Wollaston in 1801 but he failed to recognise
the significance of them, and it was their rediscovery by Joseph von Fraunhoffer in 1814, and
they still carry his name today, being known as Fraunhoffer lines
Emission lines were discovered as chemists (initially John Herschel and William Fox Talbot) starting to
examine the patterns of coloured lines given off as chemicals were burned, and gradually the emission spectra for
the elements emerged.
The connection between the emission lines and asorption lines was provided by Robert Bunsen and Gustav Kirchoff and
Kirchoff worked very hard to ensure that other people would be able to understand and use spectral analysis. In so
doing he clarified 3 important truths that tie together the absorption and emission spectra:
- A hot solid object or hot dense gas produces a continuous spectrum - a rainbow
- A hot tenuous gas produces a series of brightly coloured lines (depending on it's chemical composition) - an emission spectrum
- A hot solid body surrounded by a cooler tenuous gas gives an absorption spectrum
You can find out far more about these discoveries and how they relate to our understanding of the sun, as part
of the big story about the development of our ideas about our nearest star in the brilliantly written and easy to
read book by Dr Stuart Clark