This is one of those experiments that was expected to give this sort of result. It’s a double-check (if you will) on all the various understandings of the electron cloud model of the atom and the quantum mechanical phenomenon of entanglement (which is related to non-locality)

“When atoms form molecules, they share their outer electrons and this creates a negatively charged cloud. Here, electrons buzz around between the two positively charged nuclei, making it impossible to tell which nucleus they belong to. They are delocalized. But is this also true for the electrons located closer to the nucleus?

[…]In order to answer these questions, the scientists first removed the innermost electron located close to the nucleus from nitrogen molecules (N2), using high-energy light from a synchrotron radiation source at the Advanced Light Source at the Lawrence Berkeley National Laboratory, Berkeley, California.

It is reasonable to assume that these photo-electrons belong to one nucleus and can thus be located. They leave behind a vacancy in the inner core shell, which is then filled by an outer electron. Additionally a second electron (an Auger electron) is ejected from the molecule. This Auger electron acts as a probe that can determine exactly where the original hole was created. Both electrons, the photo-electron and the Auger electron, form an entangled state, which means that as soon as one is measured, the properties of the second are determined as well.

[…]Professor Reinhardt Dörner’s group is the first to prove the existence of such entangled states for electrons, using the COLTRIMS technology, which has been developed in Frankfurt over the last decade. With this experimental set-up, they are able to reveal the pathways of the two electrons created. In the current issue of the highly prestigious Science magazine, the physicists claim that the question of whether an electron is localized or not can only be answered for the complete system.

If the innermost electron is localized, the second electron can be assigned to either of the two nuclei. But sometimes it proves impossible to determine whether the first electron originates from the left or the right ‘atom of the first electron. In this case the second electron is also delocalized.

[Thus] it is now possible to explain the observations of the last 50 years in a unified model. Both groups – those supporting the localized theory and those endorsing a delocalized picture – are thus reconciled. Dr. Markus Schöffler, who is responsible for the measurement, sees further exciting perspectives opening up and he plans to continue his work on this topic in Berkeley, funded by a scholarship from the Alexander von Humboldt Foundation. “

Read the full article here.

Of course the fundamental question that needs to be asked. (And I’m serious here…) How do the electron know we’re looking at them? Because it seems to be the observation that changes their behavior vis-à-vis localization…