ABSTRACT
This chapter examines the underlying theory of atomic absorption and attempts to place it in perspective with two related phenomena: atomic emission and atomic fluorescence. The analysis of iron and steel was among the earliest applications of flame atomic absorption spectrophotometry. While Beer's Law is the applicable treatment for describing in general terms the linear portion of an atomic absorption calibration, the dynamic nature of the absorption region makes it impossible to apply the formula rigorously. The use of a fuel/oxidant gas flame to produce the analyte atom cloud was a key development for the evolution of atomic absorption as a generally applicable laboratory tool. With few exceptions, the only practical way to produce an atomic vapor of measurable concentration is by applying heat—by most standards, a lot of heat. The discrepancy of two orders of magnitude between the theoretical and observed line widths is accounted for by the combined influence of Doppler, electric field, and pressure effects.
