Two-body Coulomb explosion in methylacetylene in intense laser fields: double proton migration and proton/deuteron exchange

Abstract

Two-body decomposition processes of methylacetylene (CH₃CCH) and its isotopomer methyl-d₃-acetylene (CD₃CCH) in intense laser fields (790 nm, 40 fs, 5.0 × 10¹³ W cm⁻²) are investigated by the coincidence momentum imaging (CMI). In methyl-d₃-acetylene, a total of six decomposition pathways in which one of the C−C bonds is broken and a total of six pathways in which an atomic hydrogen ion (H⁺ or D⁺) or a molecular hydrogen ion (H₂⁺, HD⁺, D₃⁺, or HD₂⁺) is ejected are identified. It is revealed from the analysis of the CMI data that the migration of two deuterons as well as the exchange between a proton and a deuteron occurs prior to the two-body decomposition of a doubly charged parent molecule.