Speaker
Description
During the last 15 years, a new variant of angle-resolved photoemission spectroscopy (ARPES) has been established: photoemission orbital tomography (POT). With POT, the wave functions of a molecule's individual electronic eigenstates (the orbitals) can be reconstructed in three-dimensional space, purely on the basis of experimental data. POT thus allows us to "observe the unobservable"---remember that unlike the probability density, the wave function itself is not a quantum mechanical observable in the strict sense.
Orbitals are important in chemistry because they form the basis of chemical bonding. They also come into play whenever light-matter interaction is involved, as in optoelectronics, light harvesting or lightwave electronics, since excited states can also be described in terms of orbitals. Therefore, observing the dynamics of orbitals on their intrinsic time scales can provide deep insights into the elementary mechanisms of many crucial processes in the natural sciences. This leads to the vision of an orbital cinematography. Time-resolved photoemission orbital tomography (trPOT) has the potential provide just this. Currently, a growing community of physicists and chemists is working towards this goal, and in this talk I will report some of the milestones that have been achieved. The talk will close with an outlook on future challenges and opportunities in the field of trPOT.