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O: Fachverband Oberflächenphysik
O 69: Focussed Session: Towards a Quantitative Understanding of Complex Adsorption Structures: Surface Science goes Organic II
O 69.8: Talk
Thursday, April 3, 2014, 12:45–13:00, HSZ 01
Phase Determination of Electronic Wavefunctions utilizing the Circular Dichroism in the Angular Distribution of Photoelectrons — •Martin Graus1,2, Michael Wiessner1,2, Pascal Nigge1,2, Achim Schöll1,2, and Friedrich Reinert1,2 — 1Universität Würzburg, 97074 Würzburg, Germany — 2Karlsruher Institut für Technologie KIT, 76021 Karlsruhe, Germany
The experimental measurement of molecular orbitals by angle resolved photoelectron spectroscopy (ARPES) respectively photoemission electron microscopy (PEEM) is on the edge of providing three dimensional images of the respective electronic density distribution. This provides unprecedented insight into the structural, electronic and chemical properties of molecular materials, which are of practical relevance for future molecular electronics. A challenge in gathering the full orbital information lies in the determination of the quantum mechanical phase since it is usually lost by the conventional process of measuring solely the square of the wave function's absolute value. However, the phase is highly desired as the key parameter for the backwards Fourier Transform, which is necessary to create real space images out of the measured k-space data. We demonstrate an experimental approach to solve the phase problem taking advantage of interference patterns in the circular dichroism angular distribution (CDAD), whereby the handedness is introduced by the experimental geometry. This key experiment evidently shows that the determination of the full quantum mechanical wave function is possible by simultaneous measurement of intensity and phase.