Dependence on the Initial Configuration of Strong Field-Driven Isomerization of CH Cations and Anions

We have investigated the femtosecond laser-induced fragmentation of CH ion beam targets in various initial configurations, including acetylene (linear HCCH), vinylidene (HCC), and cis/ trans. The initial configuration is shown to have a tremendous impact on the branching ratio of acetylene-like (CH + CH ) and vinylidene-like (C + CH ) dissociation of a specific CH molecular ion. In particular, whereas CH generated from CH, a linear HCCH target, exhibits comparable levels of acetylene-like and vinylidene-like fragmentation, vinylidene or cis/ trans configuration ion beams preferably undergo vinylidene-like fragmentation, with an acetylene branching ratio ranging from 13.9% to zero.