22 June 2016 Electron diffraction imaging independent of orbital symmetry

ICFO researchers show that attosecond rescattering wavepackets retrieve molecular structure irrespective of the peculiar symmetry of a molecule’s wavefunction. Knowing the atomic structure of atoms, molecules and solids is central to understanding and manipulating their function. Laser induced electron diffraction uses a molecule’s own valence electrons to image its structure. A strong mid-IR laser field tunnel ionizes the target structure and rescatters the attosecond electron wavepacket of the molecular ion thereby acquiring structural information in its momentum distribution. A fundamental question is therefore the influence of the molecule’s wavefunction and its symmetry on the rescattering wavepacket.

In a recent study published in Nature Communications , ICFO researchers M. G. Pullen, B. Wolter, M. Baudisch, M. Sclafani, and H. Pires from the Attoscience and Ultrafast Optics Group, led by ICREA Professor at ICFO Jens Biegert, have addressed this fundamental question. Their study was conducted with colleagues from Kansas State University, the Max Planck Institute for Nuclear Physics and the Physikalisch-Technische Bundesanstalt (PTB). They investigated the geometry of both O2 and C2H2, and showed that pervious controversial claims are incorrect and that molecules can be imaged independent of their orbital symmetries. Very surprisingly, they showed that the well-known independent atom model (IAM) is not able to fully describe the observed electron scattering physics. This result is unexpected as the IAM has been the established and trusted model in the field of electron diffraction for decades. The paper provides important insights to further ultrafast atomic scale imaging with combined attosecond temporal and picometer spatial resolution to elucidade the structure and function of atoms molecules and solids.