Title : Highly rotationally excited N2 of N2O dissociation on Pd(110) surface
Abstract:
To understand the energy transfer processes associated with chemical bond breaking and successive bond formation is essential to study the dynamics of surface reactions. Although the internal states measurements of desorption products deliver much dynamical information from the surface reactions, the mechanism underlying the energy partitioning in the reactions remains mostly unclear. In this study, we employ ion imaging methods to explore the quantumstate resolved dynamics of N2O decomposition on Pd(110). We find that N2 directly desorbs with a narrow angular distribution from the decomposition of N2O adsorbed on bridge sites oriented along [001] azimuth of the surface. N2 is highly rotationally excited up to J=50 (v=0) with a large mean translational energy of 0.62 eV. By combining with the density functional theory and ab initio molecular dynamics calculations, we estimated approximately 38%–76% of the energy released (1.5 eV) from the transition state is taken up by the internal and kinetic energies of the desorbing N2. The internal energy arises from a torque transition state and
decoupled from translational energy. Applying the principle of detailed balance, we predict that rotational excitation and high incident kinetic energy of N2 can effectively reduce the reactionbarrier of N2O formation on palladium catalysis via Eley−Rideal mechanism.
Audience Take-away:
In my presentation, I will present the following important points step by step: Firstly, I will shortly introduce our experimental systems with ultra-high vacuum (UHV). We develop this system to allow a range of experiments of surface reactions and offer remarkable opportunities to advance our fundamental understanding of the dynamics and kinetics of heterogeneous catalysis. In the experiments, some reaction conditions, such as surface temperatures, the coverage of adatoms, and the energy of reactants can be well-controlled. Secondly, we will show a sample study to reveal the energy transfer mechanism in the surface reactions under the UHV conditions. In the practical catalytic reactions, due to the vast structural complexity of heterogeneous catalysts, it becomes possible if a well-definded model catalyst, such as a single crystal catalytic surface with atomic cleanness, is used. The experimental results of the surface reactions not only can set as a standard for the theoretical simulations, but also be useful for the understanding of the practical catalytic reactions. Thirdly, the revealed dynamics of the surface reactions can be used to predict the reversed reaction on the basis of the principle detailed balance. Successful examples have been reported involving the activation of small molecule such as CO2 [1] . Inspired by this study, the mechanical activation of N2 would be great interest for the ammonia industry
