7.9 x -3 1.8 x -2 Blue triangles indicate measurements at normal incidence with T n = 300 K. Black squares correspond to measurements at an incidence angle of 35°with T n = K. Red open circles represent measurements at elevated nozzle temperatures between 743 K and 763 K. Filled green circles denote measurements performed over a range of nozzle temperatures (473 K to 838 K) and for CO 2 concentrations of 30% and 0.5% in H 2 . The dashed blue curve is a fit using a S-shaped function. The numbers associated with each point are labels for identifying the experimental parameters and incident beam characteristics, described in panel (b). Note that the T n was maintained within ± 5 K of the aforementioned values across all measurements. The experimental error in the E i determination typically ranged from 2% to 8% (SI-3) when using the spatial ion imaging technique with CO as a proxy. structure, we conclude that the CO 2 dissociation leads to a saturation O-atom coverage of 0.5 ML as well. This also rules out the presence of any unwanted clean-up reactions affecting our measurements, even when using H 2 seeded beams along with a heated nozzle. It is worth pointing out that at E i higher than 3 eV we see an increased saturation coverage (0.66 ML). While this point is discussed in more detail later, it should be noted that this does not affect the O-atom coverage estimation presented here. The surface O-atom coverage build-up as a function of the incident CO 2 dose was fitted with a simple first-order kinetics model: Θ = Θ sat (1 -e -kϕ i ). Here, ϕ i corresponds to the incident CO 2 dose, and the value of saturation coverage (Θ sat ) is set to 0.5 ML. The slope of this function in the zero coverage limit (0.5 × k) gives the initial dissociative sticking probability of CO 2 on Cu(110).