Estimating Detection Limits in Ultratrace Analysis. Part III: Monitoring Atoms and Molecules with Laser-Induced Fluorescence

Laser spectroscopic methods which are sensitive enough to detect single atoms or molecules are termed single-atom detection (SAD) techniques. The detection theory of SAD methods, presented in the second paper in this series and summarized here, allows for the evaluation and comparison of these techniques. In this paper, SAD theory is applied to one task in particular: monitoring analyte atoms or molecules as they flow through a continuous-wave laser beam using fluorescence detection (CW-LIF). Several possible signal-processing methods are described and evaluated through the use of SAD theory and Monte Carlo simulations. The relative merits of these methods for SAD by CW-LIF are illustrated.