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Can molecules take pictures of themselves? That is more or less the principle underlying laser-induced electron diffraction (LIED): A laser field strips an electron from a molecule and then sends it back to report on the structure of the remaining ion. Together with a consortium including colleagues from the ICFO in Castelldefels, the Kansas State University, the Leiden University, the University of Kassel, the DESY in Hamburg, the Max Planck Institute for Nuclear Sciences in Hamburg, the PTB in Braunschweig, the Aarhus University, and the Institució Catalana de Recerca in Barcelona, ACP principal scientist Stefanie Gräfe has just published a remarkable original research article in Science on this technique. They have applied LIED to acetylene to track the cleavage of its C-H bond after double ionization. The scientists imaged the full structure of the molecule and also distinguished more rapid dissociative dynamics when it was oriented parallel rather than perpendicular to the LIED field. (Wolter et al., Science 354, 305, 2016).

Abstract: Visualizing chemical reactions as they occur requires atomic spatial and femtosecond temporal resolution. Here, we report imaging of the molecular structure of acetylene (C2H2) 9 femtoseconds after ionization. Using mid-infrared laser-induced electron diffraction (LIED), we obtained snapshots as a proton departs the [C2H2]2+ ion. By introducing an additional laser field, we also demonstrate control over the ultrafast dissociation process and resolve different bond dynamics for molecules oriented parallel versus perpendicular to the LIED field. These measurements are in excellent agreement with a quantum chemical description of field-dressed molecular dynamics.

>> link to the original article

>> link to the press release issued by the Friedrich Schiller University Jena

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