Electrons Under Observation

An international research team led by Prof. Dr. Giuseppe Sansone of the University of Freiburg’s Institute of Physics has succeeded for the first time in completely reconstructing the electronic wave functions of atoms of the element neon in a two-photon ionization process. The researchers have published their results in the journal “Nature Physics”.

Photoionization is the term used in physics for a kind of interaction of light and matter in the extreme ultraviolet range, and in the spectral range of soft X-ray radiation. This involves the atom absorbing light, that is a photon, and emitting an electron, which consists of a group of electronic waves. This process turns the atom into an ion. In the experiment, the researchers irradiated the atom using a laser, the high intensity of which enabled the atom to absorb two photons and release two electrons, which in turn produced double ionized atoms. In the process, the team altered the characteristics of the laser beam and studied how the electronic waves responded by changing form and the angle at which they moved. With their measurements, the researchers were able to visualize the released and the bound electronic wave functions of the electrons remaining in the atom. “The results allow us to characterize the interaction between atoms and intensive laser fields in the X-ray range down to the smallest aspects,” explains Sansone. “This is extremely important to future applications of the latest laser sources such as the XFEL free-electron laser in Hamburg.”

Original publication:

P.A. Carpeggiani et al. (2018): Complete reconstruction of bound and unbound electronic wavefunctions in two-photon double ionization. In: Nature Physics. DOI: 10.1038/s41567-018-0340-4