Laser-induced Coulomb explosion of 1,4-diiodobenzene molecules: Studies of isolated molecules and molecules in helium nanodroplets

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  • Lars Christiansen
  • ,
  • Jens H. Nielsen
  • ,
  • Lauge Christensen
  • ,
  • Benjamin Shepperson
  • ,
  • Dominik Pentlehner
  • ,
  • Henrik Stapelfeldt

Coulomb explosion of 1,4-diiodobenzene molecules, isolated or embedded in helium nanodroplets, is induced by irradiation with an intense femtosecond laser pulse. The recoiling ion fragments are probed by time-of-flight measurements and two-dimensional velocity map imaging. Correlation analysis of the emission directions of I+ ions recoiling from each end of the molecules reveals significant deviation from axial recoil, i.e., where the I+ ions leave strictly along the I-I symmetry axis. For isolated molecules, the relative angular distribution of the I+ ions is centered at 180 degrees, corresponding to perfect axial recoil, but with a full width at half maximum of 30.. For molecules inside He droplets, the width of the distribution increases to 45 degrees. These results provide a direct measure of the accuracy of Coulomb explosion as a probe of the spatial orientation of molecules, which is particularly relevant in connection with laser-induced molecular alignment and orientation. In addition, our studies show how it is possible to identify fragmentation pathways of the Coulomb explosion for the isolated 1,4-diiodobenzene molecules. Finally, for the 1,4-diiodobenzene molecules in He droplets, it is shown that the angular correlation between fragments from the Coulomb explosion is preserved after they have interacted with the He environment.

Original languageEnglish
Article number023411
JournalPhysical Review A
Volume93
Issue2
Number of pages12
ISSN2469-9926
DOIs
Publication statusPublished - 10 Feb 2016

    Research areas

  • COVARIANCE DATA-ACQUISITION, ANGULAR-DISTRIBUTIONS, ENHANCED IONIZATION, FRAGMENT IONS, X-RAY, PHOTOELECTRON, ALIGNMENT, FIELDS, COINCIDENCE, DYNAMICS

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