Atomic Absorption Spectrometry (AAS) is based on the principle that free atoms in the ground state can absorb light of a specific wavelength. The atomiser unit can be either a flame or a graphite furnace.
More Information HiQ: Analytical Methods - Absorption Spectrometry Application Sheet - Atomic Absorption Spectrometry (PDF) Glossary Term: Graphite Furnace Atomic Absorption Spectrometry (GF-AAS)