Anisotropic Coulomb explosion of acetylene and diacetylene derivatives

• A series of linear chain molecules was exposed to intense femtosecond laser fields.
• The carbon ion emission was blocked and altered by iodines.
• Coulomb explosion is affected by the deformation, rotation, and atomic configuration.

We investigated the significant differences in the angular distribution of carbon ions ejected from dimethylacetylenes (CH3CCCH3 and CH3CCCCCH3) and diiodoacetylenes (ICCI and ICCCCI) induced by a Coulomb explosion. The longest linear chain molecule ever reported was exposed to intense femtosecond laser fields (40 fs, <5 × 1014 Wcm−2) in this study. In the cases of the diiodoacetylenes, the angular distributions of the carbon ions were orthogonal with respect to the laser polarization direction and became narrower as the length of the molecules became longer. This is in sharp contrast to the dimethylacetylenes, in which the angular distributions of the carbon ions were parallel with respect to the laser polarization direction and became broader as the length of the molecules became longer. The specific angular distributions of carbon ions ejected from the diiodoacetylenes are explained in terms of the frozen molecular rotation, the blocking of carbon ion emission, and the bending of carbon chains at highly charged states due to the presence of iodines.

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