Femtosecond probing of persistent wave packet motion in dissociative reactions: up to 40 ps

Femtosecond probing of nuclear motion in an alkali halide (NaI) reaction reveals a persistent wave packet, recurring at long times up to 40 ps. The detection of both "free" Na atoms and "transient" [Na…I]^(≠*) indicates non-exponential dynamics through the crossing zone of the covalent and ionic potential energy curves. These observations are related to the nature of the motion, and the level structure making the packet.