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Abstract of [Li21a]

[Li21a]
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Pulse energy and pulse duration effects in the ionization and fragmentation of iodomethane by ultraintense hard x rays

Xiang Li, Ludger Inhester, Seyyed J. Robatjazi, Benjamin Erk, Rebecca Boll, Kota Hanasaki, Koudai Toyota, Yajiang Hao, Cedric Bomme, Benedikt Rudek, Lutz Foucar, Stephen H. Southworth, Carl S. Lehmann, Bertold Krässig, Tatiana Marchenko, Marc Simon, Kiyoshi Ueda, Ken R. Ferguson, Maximilian Bucher, Tais Gorkhover, Sebastian Carron, Roberto Alonso-Mori, Jason E. Koglin, Jonathan Correa, Garth J. Williams, Sébastien Boutet, Linda Young, Christoph Bostedt, Sang-Kil Son, Robin Santra, Daniel Rolles, and Artem Rudenko

Phys. Rev. Lett. 127, 093202 (2021)

[bib][BibTeX][pdf][pdf][link]doi:10.1103/PhysRevLett.127.093202

The interaction of intense femtosecond x-ray pulses with molecules sensitively depends on the interplay between multiple photo-absorptions, Auger decay, charge rearrangement and nuclear motion. Here, we report on a combined experimental and theoretical study of the ionization and fragmentation of iodomethane (CH3I) by ultra-intense (∼1019 W/cm2) x-ray pulses at 8.3 keV, demonstrating how these dynamics depend on the x-ray pulse energy and duration. We show that the timing of multiple ionization steps leading to a particular reaction product and, thus, the product¡¯s final kinetic energy, is determined by the pulse duration rather than the pulse energy or intensity. While the overall degree of ionization is mainly defined by the pulse energy, our measurement reveals that the yield of the fragments with the highest charge states is enhanced for short pulse durations, in contrast to earlier observations for atoms and small molecules in the soft x-ray domain. We attribute this effect to a decreased charge transfer efficiency at larger internuclear separations, which are reached during longer pulses.

Tags: CH3I, ionization, fragmentation, CREXIM, XMOLECULE, LCLS, experiment, XFEL, CFEL, DESY


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