The very existence of the electron-electron interaction is responsible for the absorption of a single photon that leads to multi electron emission. A prominent example for two electrons is the emission of a photoelectron and a concomitant Auger electron. The emission of three or four electrons upon single photon absorption is also well-documented. Multiple electron emission events have experienced renewed interest with the availability of intense and ultrashort light pulses from synchrotron and laser sources. These allow to address fundamental questions on the time evolution of the electron dynamics on the attosecond (as) timescale.

We discuss a novel emission process which occurs when the photon energy matches twice the binding energy of a core state. The conventional process of single core electron ionization followed by emission of a single Auger electron, can be accompanied by a competing two electron resonant Raman process. As depicted in the cartoon the photon lifts an electron pair above the Fermi level, but below the vacuum level. In an auto ionizing process an electron pair is emitted.

Frank Oliver Schumann

Frank Schumann studied physics at the RWTH Aachen and received his PhD degree from the University of Cambridge/UK in 1994. From 1994-1999 he was a post-doc at the Pennsylvania State University and Lawrence Livermore National lab. In 1999 he lead of a junior research group at the FU Berlin. In 2004 he joined the Max-Planck Institute of Microstructure Physics as a senior scientist and obtained his habilitation degree from the Martin-Luther University Halle in 2012.

Research Experience

Frank Schumann is a surface scientist and investigated the magnetic properties of 2D systems via a variety of techniques including synchrotron radiation. Upon joining the MPI-Halle he shifted his research to the investigation of the electron-electron interaction at surfaces. This was accomplished by utilizing advanced electron spectroscopy. In the future he will conduct research using a low temperature STM to explore the on-surface synthesis of 2D carbon nanostructures.