Dissociative Chemisorption of C${\mathrm{H}}_4$ on W(110): Dramatic Activation by Initial Kinetic Energy

The initial dissociative chemisorption probability of C${\mathrm{H}}_4$ on a W(110) surface is found to increase by ∼${10}^5$ on raising of the C${\mathrm{H}}_4$ incident translational energy, reaching a value of ∼0.2 at 100 kJ/mole. This is by far the largest such effect (by ∼${10}^3$) reported to date and is consistent with a mechanism dominated by quantum tunneling, a conclusion further supported by measurements for C${\mathrm{D}}_4$.