During ionization in a strong laser field, an electron is released from a molecule. So far, physicists believed that this is the weakest bound electron in the molecule. A research group has now demonstrated in an experiment that even more strongly bound electrons are released by the ionization in a strong laser field. This new understanding not only advances attosecond research, but also brings researchers closer to the goal of controlling chemical processes. The researchers report on these findings in the journal Science on 16 March 2012.
In one molecule, the electrons move in different orbitals, with no more than two electrons in each orbital. The orbitals have different energy levels. For the highest occupied orbital, the least amount of energy is needed to extract an electron. Therefore, it is obvious that during ionization an electron separates from the highest occupied orbit. However, theoreticians have long had doubts about this thesis because many observations could not be explained well. Although there was evidence in experiments that electrons were released from a lower orbit, so many effects were superimposed that the clear proof was missing. Prof. Marc Vrakking, Director at the Max-Born-Institut (MBI) in Berlin, explains: "We have now delivered this proof with our experiment."