  In the general framework of open quantum systems, we assess the impact of the
pulse area on single and double quantum coherence (1QC and 2QC) signals
extracted from fluorescence emitted by dilute thermal gases. We show that 1QC
and 2QC signals are periodic functions of the pulse area, with distinctive
features which reflect the particles' interactions via photon exchange, the
polarizations of the laser pulses, and the observation direction.
