Role of proton dynamics in efficient photoionization of hydrocarbon molecules

Xinhua Xie, Stefan Roither, Markus Schöffler, Huailiang Xu, Sergiy Bubin, Erik Lötstedt, Sonia Erattuphuza, Atsushi Iwasaki, Daniil Kartashov, Kálmán Varga, Gerhard G. Paulus, Andrius Baltuška, Kaoru Yamanouchi, Markus Kitzler

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21 Citations (Scopus)


We experimentally investigate the ionization mechanism behind the formation of remarkably high charge states observed in the laser-pulse-induced fragmentation of different hydrocarbon molecules by Roither et al. [Phys. Rev. Lett. 106, 163001 (2011)PRLTAO0031-900710.1103/PhysRevLett.106.163001], who suggested enhanced ionization occurring at multiple C-H bonds as the underlying ionization mechanism. Using multiparticle coincidence momentum imaging we measure the yield of multiply charged fragmenting ethylene and acetylene molecules at several intensities and pulse durations ranging from the few-cycle regime to 25 fs. We observe, at constant intensity, a strong increase of the proton energy with increasing laser pulse duration. It is shown that this is caused by a strong increase in the yield of highly charged parent molecular ions with pulse duration. Based on experimental evidence we explain this increase by the necessary population of precursor states in the parent ion that feature fast C-H stretch dynamics to the critical internuclear distance, where efficient ionization via enhanced ionization takes place. For increasing pulse duration these precursor ionic states are more efficiently populated, which leads in turn to a higher enhanced-ionization probability for longer pulses. Our work provides experimental evidence for the existence of a multiple-bond version of enhanced ionization in polyatomic molecules.

Original languageEnglish
Article number023429
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number2
Publication statusPublished - Feb 26 2014

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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