https://doi.org/10.1351/goldbook.O04272
The intersection of the optical beam and that part of the flame where the net signal is at least half of the maximum net signal. The characteristics of the observation space depend on the temperature of the flame, the @[email protected] of the gases and the properties of the processed fluid (presence of @[email protected] for instance). The observation space in atomic absorption is analogous to the observation space of a cuvette in molecular absorption @[email protected]
See also:
observation volume (in flame emission and absorption spectrometry)