International Collaboration in Chemistry: Control of Ultrafast EUV-induced Chemical Reactions
Zusammenfassung der Projektergebnisse
Within this project, a collaboration with the J. R. Macdonald Laboratory (JRML) at Kansas State University in the United States, we have, together with other German and US collaborators implemented single-shot, carrier-envelope-phase (CEP) tagging in combination with cold-target, recoilion-momentum spectroscopy (COLTRIMS) and velocity-map imaging (VMI) at kilohertz repetition rates. The new approach permits long data acquisition times (multiple days) and therefore provides unprecedented signal-to-noise ratios in CEP-dependent measurements. We have applied this new technique to measure CEP-dependent, correlated two-electron emission in the non-sequential double ionization (NSDI) of rare gases and molecules such as N2, NO, and C2H2 (acetylene) in intense, few-cycle laser fields. Using this tagging approach, we were able to precisely measure the CEP-dependent ionization yields in all these cases. The measurements on rare gases serve as a benchmark for theoretical modeling and molecular experiments. In the case of Ar, we find that recollision excitation with subsequent ionization (RESI) is the dominating mechanism for the release of two electrons at an instantaneous peak intensity of 3x1014 W/cm2, see also the press release at: http://www.mpq.mpg.de/cms/mpq/en/news/press/archiv/2012/12_05_08.html. The cross-like structure observed in electron-electron correlation maps for NSDI of Ar in few-cycle laser fields, together with our semi-classical modeling, suggests that ionization depletion is an important mechanism which has been neglected in previous theoretical models. We find that this mechanism is universal and also applies to the NSDI of N2, where very similar correlation maps are observed despite different excitation energies. We have furthermore investigated other molecular systems including CO, NO, and C2H2, where we track the CEP control of the dissociation of these molecules in various charge states. We have extended the CEP control of molecular reactions to the mid-infrared (MIR) and see (in the case of D2) that using longer wavelengths offers a route to increase the asymmetric ejection of fragments in its dissociative single ionization. We have contributed to the realization of femtosecond EUV pump – EUV probe experiments at the Free Electron Laser in Hamburg (FLASH) and studied the dissociation pathways after EUV ionization and excitation in strong EUV fields of several molecules with this approach. Among the studied molecules are N2, O2, and C2H2. Within the collaboration with the Kansas group we have investigated the same (O2) and other molecules (CO) using EUV pump – IR probe spectroscopy, where an intense IR pulse can induce the strong-field decay of excited states of the molecular ions which leads to their dissociation.
Projektbezogene Publikationen (Auswahl)
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“Dynamic modification of the fragmentation of COq+ excited states generated with high-order harmonics”, Phys. Rev. A 82, 043410 (2010)
W. Cao, S. De, K.P. Singh, S. Chen, M. Schöffler, A. Alnaser, I. Bocharova, G. Laurent, D. Ray, S. Zherebtsov, M.F. Kling, I. Ben-Itzhak, I.V. Litvinyuk , A. Belkacem, T. Osipov, T. Rescigno, and C.L. Cocke
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“Dynamic modification of the fragmentation of autoionizing states of O2+”, Phys. Rev. A 84, 053406 (2011)
W. Cao, G. Laurent, S. De, M. Schöffler, T. Jahnke, A.S. Alnaser, I.A. Bocharova, C. Stuck, D. Ray, M.F. Kling, I. Ben-Itzhak, Th. Weber, A.L. Landers, A. Belkacem, R. Dörner, A.E. Orel, T.N. Rescigno, and C.L. Cocke
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“Single-shot velocity-map imaging of attosecond light-field control at kilohertz rate”, Rev. Sci. Instrum. 82, 093109 (2011)
F. Süßmann, S. Zherebtsov, J. Plenge, Nora G. Johnson, M. Kübel, A.M. Sayler, V. Mondes, C. Graf, E. Rühl, G.G. Paulus, D. Schmischke, P. Swrschek, and M.F. Kling
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“Attosecond tracing of correlated electron-emission in nonsequential double ionization”, Nature Communications 3:813 (2012)
Boris Bergues, Matthias Kübel, Nora G. Johnson, Bettina Fischer, Nicolas Camus, Kelsie J. Betsch, Oliver Herrwerth, Arne Senftleben, A. Max Sayler, Tim Rathje, Itzik Ben-Itzhak, Robert R. Jones, Gerhard G. Paulus, Ferenc Krausz, Robert Moshammer, Joachim Ullrich, and Matthias F. Kling
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“Controlled directional ion emission from several fragmentation channels of CO driven by a fewcycle laser field”, Phys. Rev. A 86, 063403 (2012)
K.J. Betsch, Nora G. Johnson, B. Bergues, M. Kübel, O. Herrwerth, A. Senftleben, I. Ben-Itzhak, G.G. Paulus, R. Moshammer, J. Ullrich, M.F. Kling, and R.R. Jones
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“Subcycle controlled charge-directed reactivity with few-cycle midinfrared pulses”, Phys. Rev. Lett 108, 063002 (2012)
I. Znakovskaya, P. von den Hoff, G. Marcus, S. Zherebtsov, B. Bergues, X. Gu, Y. Deng, M.J.J. Vrakking, R. Kienberger, F. Krausz, R. de Vivie-Riedle, and M.F. Kling
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“Tracing nuclear wave-packet dynamics in singly and doubly charged states of N2 and O2 with XUV- pump–XUV-probe experiments”, Phys. Rev. A 86, 013415 (2012)
M. Magrakvelidze, O. Herrwerth, Y.H. Jiang, A. Rudenko, M. Kurka, L. Foucar, K.U. Kühnel, M. Kübel, Nora G. Johnson, C.D. Schröter, S. Düsterer, R. Treusch, M. Lezius, I. Ben-Itzhak, R. Moshammer, J. Ullrich, M.F. Kling, and U. Thumm
