A new probe for coherent many-body dynamics: Nonergodic molecules in continuum

We present a simple physical explanation that measurements of the collision cross-sections with pure energy resolution can provide information on the reaction dynamics equivalent to that obtained using real-time methods of femtochemistry. For nuclear collisions, the method provides a time resolution of ∼ 10^-21 sec. The method is sensitive enough to distinguish between the different scenarios of rotational dephasing for the highly-excited nuclear molecules, with strongly overlapping resonances, formed in ¹²C + ²⁴Mg scattering. We find that the dephasing is much slower than the intra-molecular energy redistribution. This reveals unusual states - nonergodic molecules in continuum. Anomalously long dephasing times observed in highly-excited polyatomic molecules may reflect this new type of nonergodicity.