Dynamic Solvation Effects in I_2~+(CO_2)_n Impact onto Solid Surface - Wedge and Cage Effects

摘要

Novel mechanisms were found to operate in dissociation of I_2~- embedded in a CO_2 cluster, I_2~+(CO_2)_n by its impact onto a silicon surface. The bond of I_2~- is split by a CO_2 molecule located halfway between the two iodine atoms in the parent I_2~+(CO_2)_n, as if the CO_2 molecule behaves as a molecular 'wedge' (wedge effect). On the other hand, the dissociation of I_2~- is suppressed when it is caged in a complete CO_2 molecular shell (cage effect). The wedge effect was also demonstrated by a molecular-dynamics simulation. By measuring the surface-parallel component of the translational energy of the I_2~- and I~- product unions, it was concluded that a 'quasi-equilibrium' was established on the surface before the product anions leave from it. The translational-energy distribution of the product anions also shows the cage effect.