@article{ChristiansenNielsenChristensenetal.2016, author = {Christiansen, Lars and Nielsen, Jens H. and Christensen, Lauge and Shepperson, Benjamin and Pentlehner, Dominik and Stapelfeldt, Henrik}, title = {Laser-induced Coulomb explosion of 1,4-diiodobenzene molecules: Studies of isolated molecules and molecules in helium nanodroplets}, series = {Physical Review A}, journal = {Physical Review A}, number = {93}, year = {2016}, abstract = {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∘, 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∘. 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.}, language = {en} }