J. Phys.: Conf. Ser. 1412, 232012 (2020)
Vibrational autodetachment from hot copper dimer anions: breakdown of the Born-Oppenheimer approximation
E K Anderson1, A F Schmidt-May2, P K Najeeb1, G Eklund1, S Rosén1, M H Stockett1, K Chartkunchand1, M Kaminska1, K Hansen3, H Cederquist1, H Zettergren1 and H T Schmidt1
1 Department of Physics, Stockholm University, S-10691, Stockholm Sweden
2 Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
3 Center for Joint Quantum Studies and Department of Physics, Tianjin University, Tianjin 300072, China
The decay of hot copper dimer anions is studied in a cryogenic storage ring. We detect atomic anion and neutral products and determine the fragmentation and vibrational autodetachment (VAD) rates separately. For short storage times the dimer anions predominantly decay by fragmentation of highly rotationally excited ions by tunneling through the rotational barrier. For storage times exceeding 100 ms, however, VAD is dominating. This process is driven by the very weak direct coupling between nuclear and electronic degrees of freedom.