atomic absorption spectroscopy flame atomic absorption spectroscopy F-AAS FAAS An atomic absorption spectroscopy in which the sample is aspirated, aerosolised, and mixed with combustible gases, such as acetylene and air or acetylene and nitrous oxide, and then ignited and atomised in a flame whose temperature ranges from 2100–2800 °C. During combustion, atoms of the element of interest in the sample absorb light at characteristic wavelengths. CHMO:0000243 flame atomic absorption spectroscopy