Laser-induced Coulomb explosion dynamics of H₂ molecules in helium nanodroplets

We investigate the Coulomb explosion dynamics of H₂ molecules embedded in helium nanodroplets, induced by an intense ultraviolet femtosecond laser pulse. By employing ion-ion coincidence and momentum correlation spectroscopy, we identify the Coulomb-exploded double ionization of H₂ molecules within the droplets. Our results demonstrate that the collisions between dissociating H⁺ ions and surrounding He atoms significantly alter both the kinetic energy distributions and the emission direction of the ion fragments. Notably, the HeH⁺ fragments originating from the Coulomb explosion channel exhibit higher kinetic energies in larger droplets, a phenomenon driven by the solvation dynamics that depend on the fragment’s kinetic energy and droplet size. This study provides deep insights into the translation, dissociation, and solvation processes of light impurities in quantum liquid, underscoring the critical role of droplet size in shaping fragment kinetics during these processes.