Atomic florescence (AF) is a technique used for elemental
analysis. Energy absorbed by an atom will cause an electron to move from the
preferred level (ground state) to a higher energy level (excited state), and as
the electron returns to the ground state energy is released as fluorescence. The
technique is most effective for elements that for readily hydrides (e.g.
arsenic and selenium), or are volatile at or near ambient temperature (e.g.
mercury) as these elements can be easily stripped from solution and carried to
the detector in gaseous phase free from molecular interferences. The technique
is used almost exclusively for ultra-trace detection of mercury in
environmental samples, with detection limits in the sub-part per trillion range.
AF instruments have
limited availability. Typically atomic
emission and atomic absorption instruments are used to acquire elemental data
with comparable sensitivity.