Imaging the Breakdown of Molecular-Frame Dynamics through Rotational   Uncoupling
  We demonstrate the breakdown of molecular-frame dynamics induced by the uncoupling of molecular rotation from electronic motion in molecular Rydberg states. We observe this non-Born-Oppenheimer regime in the time domain through photoelectron imaging of a coherent molecular Rydberg wave packet in $\textrm{N}_2$. The photoelectron angular distribution shows a radically different time evolution than that of a typical molecular-frame-fixed electron orbital, revealing the uncoupled motion of the electron as it precesses around the $averaged$ anisotropic potential of the rotating ion-core. 
Lucas J. Zipp, Adi Natan, Philip H. Bucksbaum
physics.atm-clus