Dissociation Dynamics\nof CO<sub>2</sub> on Cu(110)\nStudied over a Wide Range of Incident Energies

In this work, we have studied the dissociation dynamics\nof CO<sub>2</sub> on a Cu(110) surface using molecular beams with\nincidence\nenergies ranging from 0.28 to 4.6 eV. The incident energy dependence\nof the initial dissociative sticking probabilities (<i>S</i><sub>0</sub>) of CO<sub>2</sub> showed two distinct characteristics.\nAt first, <i>S</i><sub>0</sub> exhibits a rapid increase\nfrom 1.8 × 10<sup>–4</sup> at 0.28 eV to more than 150-fold\nat 2 eV. Beyond this, only a small increase by less than a factor\nof 1.5 was observed in the 2–4.6 eV range, with the <i>S</i><sub>0</sub> being 4.1 × 10<sup>–2</sup> at\n4.6 eV. Incident angle-dependent measurements reveal total energy\nscaling to be followed. Measurements using a heated nozzle showed\nno observable enhancement in <i>S</i><sub>0</sub> due to\nthe vibrational energy of the incident molecules, with the upper limit\nof vibrational efficacy estimated to be 0.25. Furthermore, an increase\nin O atom saturation coverage (resulting from CO<sub>2</sub> dissociation)\nfrom 0.5 to 0.66 ML was observed at high impact energies (>3 eV),\nsuggesting that newer dissociation sites become accessible at higher\nenergies.