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Wolter B, Pullen MG, Le AT, Baudisch M, Doblhoff-Dier K, Senftleben A, Hemmer M, Schröter CD, Ullrich J, Pfeifer T, Moshammer R, Gräfe S, Vendrell O, Lin CD, Biegert J. Ultrafast electron diffraction imaging of bond breaking in di-ionized acetylene. Science 2017; 354:308-312. [PMID: 27846561 DOI: 10.1126/science.aah3429] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/19/2016] [Indexed: 01/27/2023]
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.
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Affiliation(s)
- B Wolter
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - M G Pullen
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - A-T Le
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS 66506-2604, USA
| | - M Baudisch
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - K Doblhoff-Dier
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Post Office Box 9502, 2300 RA Leiden, Netherlands
| | - A Senftleben
- Universität Kassel, Institut für Physik und CINSaT, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - M Hemmer
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain.,Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron (DESY), Centre for Ultrafast Imaging (CUI), 22607 Hamburg, Germany
| | - C D Schröter
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - J Ullrich
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.,Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany
| | - T Pfeifer
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - R Moshammer
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - S Gräfe
- Institute for Physical Chemistry, Friedrich-Schiller University Jena, 07743 Jena, Germany.,Abbe Center of Photonics, Friedrich-Schiller-University Jena, 07743 Jena, Germany
| | - O Vendrell
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron (DESY), Centre for Ultrafast Imaging (CUI), 22607 Hamburg, Germany.,Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - C D Lin
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS 66506-2604, USA
| | - J Biegert
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain. .,Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, 08010 Barcelona, Spain
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Engels B, Hanrath M, Lennartz C. Individually selecting multi-reference CI and its application to biradicalic cyclizations. COMPUTERS & CHEMISTRY 2001; 25:15-38. [PMID: 11153798 DOI: 10.1016/s0097-8485(00)00086-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the present review a new algorithm to perform individually selecting MR-CI calculations is discussed. The new algorithm exploits the advantages arising from the subdivision of the molecular orbitals (MOs) into an internal and an external part and avoids the recalculation of representation matrices by the use of a specially designed cache. With the new algorithms we are able to perform calculations including more than 10 million selected configurations state functions (CSFs) as a matter of routine. As an example for the possibilities of the new approach the regioselectivity of thermal biradical cyclizations (C2-C7 vs. C2-C6 cyclization) is investigated in the second part of the present work. After studying the accuracy of various quantum chemical methods (MR-CI, density functional theory, and coupled cluster approaches) using (Z)-1,2,4 Heptatriene-6-yne as a model system the influence of substituents (R = H, Ph, t-Bu, NH2) on the regioselectivity is investigated. Our results rationalize the switch between the two biradical cyclizations on the basis of mainly steric (t-Bu) or electronic (Ph) substituent effects. Moreover, the results for R = NH2 predict that the activation energy of the C2-C6 cyclization can be lowered even more. However, a change in the reaction mechanism is found.
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Affiliation(s)
- B Engels
- Institut für Organische Chemie, Universität Würzburg, Germany
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