Molecular double slit and the recoil effect
Final Report Abstract
The idea of the proposal built on the fact that the ejection of a photoelectron wave from a homonuclear diatomic molecule resembles the situation behind a double slit. Two coherent photoelectrons waves emerging from the two indistinguishable centers of the molecule lead to interferences in the electron angular distribution. The proposal had suggested to explore the role of the recoil momentum imparted by the emitted photoelectron on the molecule and to test if this momentum transfer acts as a “which way marker” leading to degradation of the interference contrast. In the project, we found that the electron recoil momentum does indeed modify the molecular dissociation dynamics but does not quench the interference. It alters the height of the interference maxima. Guided by theory, which had in the first place been prompted by discussions and preliminary results from our team, we made a further unexpected discovery: at very low electron energies the electrons, acts back on the molecule and breaks the symmetry. At the high photon energies, we additionally explored double ionization and found a close relationship to the quantum optics phenomenon of two-particle interference. Finally, our results lead to view high energy photoionization from a very different perspective. Instead of considering the interference, as many have done before us, we refer to the Born approximation. At high photon energies, the outgoing photoelectron can be approximated by a plane wave. Thus, photoionization resembles a Fourier transform. Together with Fernando Martin and his team, we could show that the angular distribution gives a direct image of the ground state wavefunction in momentum space. We could show that for the two electrons in H2 the coincident detection of a fast photoelectron with the dissociation product allows to directly image the square of the correlated ground state wavefunction. Our method of correlation imaging turned out to be so sensitive that we could even image a small fraction of the wavefunction which is not captured in the Hartree Fock approximation for H2.
Publications
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Delocalization of a Vacancy across Two Neon Atoms Bound by the van der Waals Force. Physical Review Letters, 117, 263001 (2016)
H. Sann, C. Schober, A. Mhamdi, F. Trinter, C. Müller, S. K. Semenov, M. Stener, M. Waitz, T. Bauer, R. Wallauer, C. Goihl, J. Titze, F. Afaneh, L. Ph. H. Schmidt, M. Kunitski, H. Schmidt-Böcking, Ph. V. Demekhin, N. A. Cherepkov, M. S. Schöffler, T. Jahnke, R. Dörner
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Electron Localization in Dissociating H2+ by Retroaction of a Photoelectron onto Its Source. Physical Review Letters, 116, 043001 (2016)
M. Waitz, D. Aslitürk, N. Wechselberger, H. K. Gill, J. Rist, F. Wiegandt, C. Goihl, G. Kastirke, M. Weller, T. Bauer, D. Metz, F. P. Sturm, J. Voigtsberger, Zeller, F. Trinter, G. Schiwietz, T. Weber, J. B. Williams, M. S. Schöffler, L. Ph. H. Schmidt, T. Jahnke, R. Dörner
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Two-Particle Interference of Electron Pairs on a Molecular Level. Physical Review Letters, 117, 083002 (2016)
M. Waitz, D. Metz, J. Lower, C. Schober, M. Keiling, M. Pitzer, K. Mertens, M. Martins, J. Viefhaus, S. Klumpp, T. Weber, H. Schmidt-Böcking, L. Ph. H. Schmidt, F. Morales, S. Miyabe, T. N. Rescigno, C.W. McCurdy, F. Martín, J. B. Williams, M. S. Schöffler, T. Jahnke and R. Dörner
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Imaging of the correlated two-electron wave function of a H2 molecule. Nature Communications, 2266 (December 2017)
M. Waitz, R.Y. Bello, D. Metz, J. Lower, F. Trinter, C. Schober, M. Keiling, U. Lenz, M. Pitzer, K. Mertens, M. Martins, J. Viefhaus, S. Klumpp, T. Weber, L. Ph. H. Schmidt, J. B. Williams, M. S.Schöffler, V. V. Serov, A. S. Kheifets, L. Argenti, A. Palacios, F. Martin, T. Jahnke, and R. Dörner
