Exploring strong-field isomerization and dissociation of acetylene anion and cation targets*

Over the past several years, acetylene has generated substantial interest as a prototype system for examining isomerization processes, specifically hydrogen migration. Using coincidence 3D momentum imaging, we investigate intense ultrafast laser-induced isomerization and two-body fragmentation of keV beams of various charge states of acetylene, including C$_2$H$_2^-$, C$_2$H$_2^+$, and C$_2$H$_2^{2+}$. Whereas the vast majority of previous work on strong field isomerization and fragmentation of acetylene has necessarily involved ionization step(s), by focusing on dissociation, we ensure that the dynamics ensue within a single molecular ion species, potentially simplifying interpretation. Also, we find the behavior of the branching ratios of the acetylene (CH$^{q_1}$+CH$^{q_2}$) and vinylidene (C$^{q_1}$+CH$_2^{q_2}$) dissociation channels to depend strongly upon the initial ionic species.