Strong-field dissociative ionization of a linear triatomic molecule: Relationship between Coulomb-explosion energies and bond angle

Abstract

Correlation images of the symmetric six-electron Coulomb-explosion channel of ${\mathrm{CO}}_{2}$ were used to isolate specific geometries (linear and bent) for angular-resolved analysis of the Coulomb-explosion energy in the framework of both the critical radius ${R}_{c}$ and dynamic screening models. We show that it is possible to connect the ${R}_{c}$ and screening pictures through a single parameter, a charge defect $\ensuremath{\sigma},$ which depends on the charge state and the ratio between ${R}_{c}$ and the equilibrium bond length. Our data show that ${R}_{c}$ and hence $\ensuremath{\sigma}$ are slow varying functions of bond angle between $145\ifmmode^\circ\else\textdegree\fi{}$ and $180\ifmmode^\circ\else\textdegree\fi{}$ with ${R}_{c}\ensuremath{\sim}4\mathrm{a}.\mathrm{u}.$ and $\ensuremath{\sigma}\ensuremath{\sim}0.5$ for the symmetric six-electron channel of ${\mathrm{CO}}_{2}.$ In the ${R}_{c}$ picture, the experimental value for ${R}_{c}$ is consistent with a theoretical value associated with ${\mathrm{CO}}_{2}^{3+},$ which is considerably smaller than that associated with ${\mathrm{CO}}_{2}^{+}(\ensuremath{\sim}6\mathrm{a}.\mathrm{u}.).$