Hydrogen scrambling in ethane induced by intense laser fields: Statistical analysis of coincidence events

Two-body Coulomb explosion processes of ethane (CH3CH3) and its isotopomers (CD3CD3 and CH3CD3) induced by an intense laser field (800 nm, 1.0 x 10(14) W/cm(2)) with three different pulse durations (40 fs, 80 fs, and 120 fs) are investigated by a coincidence momentum imaging method. On the basis of statistical treatment of the coincidence data, the contributions from false coincidence events are estimated and the relative yields of the decomposition pathways are determined with sufficiently small uncertainties. The branching ratios of the two body decomposition pathways of CH3CD3 from which triatomic hydrogen molecular ions (H-3(+), H2D+, HD2+, D-3(+)) are ejected show that protons and deuterons within CH3CD3 are scrambled almost statistically prior to the ejection of a triatomic hydrogen molecular ion. The branching ratios were estimated by statistical Rice-Ramsperger-Kassel-Marcus calculations by assuming a transition state with a hindered-rotation of a diatomic hydrogen moiety. The hydrogen scrambling dynamics followed by the two body decomposition processes are discussed also by using the anisotropies in the ejection directions of the fragment ions and the kinetic energy distribution of the two body decomposition pathways. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4720503]