Enhanced ionisation of polyatomic molecules in intense laser pulses is due to energy upshift and field coupling of multiple orbitals

Sonia Erattupuzha, Cody L. Covington, Arthur Russakoff, Erik Lötstedt, Seyedreza Larimian, Václav Hanus, Sergiy Bubin, Markus Koch, Stefanie Gräfe, Andrius Baltuška, Xinhua Xie, Kaoru Yamanouchi, Kálmán Varga, Markus Kitzler

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13 Citations (Scopus)

Abstract

We present the results of a combined experimental and numerical study on strong-field ionisation of acetylene performed with the aim of identifying the mechanism behind the previously reported surprisingly large multi-electron ionisation probabilities of polyatomic molecules. Using coincidence momentum imaging techniques and time-dependent density functional simulations, we show that the reported efficient ionisation is due to the combined action of a significant geometrically induced energy upshift of the most relevant valence orbitals as the C-H distance stretches beyond about two times the equilibrium distance, and a strong increase in the coupling between multiple molecular orbitals concomitant with this stretch motion. The identified enhanced ionisation mechanism, which we refer to as EIC-MOUSE, is only effective for molecules aligned close to parallel to the laser polarisation direction, and is inhibited for perpendicularly aligned molecules because of a suppression of the C-H stretch motion during the onset of ionisation.

Original languageEnglish
Article number125601
JournalJournal of Physics B: Atomic, Molecular and Optical Physics
Volume50
Issue number12
DOIs
Publication statusPublished - May 31 2017

Keywords

  • Coupling of multiple orbitals
  • enhanced ionisation
  • multiple ionisation and fragmentation of polyatomic molecules

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics

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    Erattupuzha, S., Covington, C. L., Russakoff, A., Lötstedt, E., Larimian, S., Hanus, V., Bubin, S., Koch, M., Gräfe, S., Baltuška, A., Xie, X., Yamanouchi, K., Varga, K., & Kitzler, M. (2017). Enhanced ionisation of polyatomic molecules in intense laser pulses is due to energy upshift and field coupling of multiple orbitals. Journal of Physics B: Atomic, Molecular and Optical Physics, 50(12), [125601]. https://doi.org/10.1088/1361-6455/aa7098