Mapping spin-orbit activated interchannel coupling

¹ Deutsches Elektronen-Synchrotron DESY - Notkestrasse 85, D-22607 Hamburg, Germany
² Fakultät für Physik, Universität Bielefeld - Universitätsstrasse 25, D-33615 Bielefeld, Germany
³ Light Source - Chilton, Didcot, Oxfordshire OX11 0DE, UK
⁴ Department of Physics, University of Regensburg - D-93040 Regensburg, Germany
⁵ Electronic Properties and Superconductivity, Institute of Physics, Humboldt-University of Berlin D-12489, Germany
⁶ Helmholtz-Institut Jena - Max-Wien-Platz 1, D-07743 Jena, Germany
⁷ Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena D-07743 Jena, Germany

Received: 18 February 2014
Accepted: 25 March 2014

Abstract

Recent advances in the generation of femtosecond extreme ultraviolet pulses have opened up the possibility to study final-state wave functions in photoemission experiments. Here, we investigate, for the first time using femtosecond time-resolved core-level spectroscopy, the feasibility of observing the buildup of a state correlation in a direct time domain. Giant changes in the ratio of photoemission cross-sections of spin-orbit split core states, the branching ratio, are identified. Multi-configuration Dirac-Fock calculations show that the origin of the branching ratio deviation is due to strong core-valence interactions. The possibility to tune this interaction by charge transfer offers intriguing opportunities to study correlation effects in solid and molecular systems in the future.