Figure 1.

(a) The geometry and timing used in the stimulated-photon echo experiment. Two detectors collect the light emitted into the k_α = −k₁ + k₂ + k₃ and the k_β = k₁ − k₂ + k₃ directions. (b) Stimulated-photon echo signal obtained for CA–N₃⁻ in the k_α direction plotted against the delay time between pulse 1 and pulse 2 (τ) and pulse 2 and pulse 3 (T).