Quantum Anomaly Dissociation of Quasibound States Near the Saddle-Point   Ionization Limit of a Rydberg Electron in Crossed Electric and Magnetic   Fields
  In the combination of crossed electric and magnetic fields and the Coulomb field of the atomic nucleus the spectrum of the Rydberg electron in the vicinity of the Stark saddle-point are investigated at a quantum mechanical level. The results expose a quantum anomaly dissociation: quasibound states near and above the saddle-point ionization limit predicted at the semi-classical level disappear at a quantum mechanical level. 
Jian-Zu Zhang, Li-Ming He, Yun-Xia Zhu