First principles rates for surface chemistry employing exact transition state theory: application to recombinative desorption of hydrogen from Cu(111).

We present first principles calculations of the reactive flux for thermal recombinative desorption of hydrogen from Cu(111). We follow a theoretical paradigm used successfully for gas phase reactions, where electronic structure theory (DFT-GGA) is combined with transition state theory (TST). Classical ab initio molecular dynamics trajectories initiated from a thermal distribution near the transition state provide dynamical corrections to the desorption rate.

Associative desorption of hydrogen isotopologues from copper surfaces: Characterization of two reaction mechanisms.

We report quantum-state resolved measurements of angular and velocity distributions of the associative desorption of H, HD, and D from Cu(111) and Cu(211) surfaces. The desorbing molecules have bimodal velocity distributions comprising a "fast" channel and a "slow" channel on both facets. The "fast channel" is promoted by both hydrogen incidence translational and vibrational energy, while the "slow channel" is promoted by vibrational energy but inhibited by translational energy.

Evidence for Electron-Hole Pair Excitation in the Associative Desorption of H and D from Au(111).

The dissociative adsorption reaction of hydrogen on noble metals is believed to be well-described within the Born-Oppenheimer approximation. In this work, we have experimentally derived translational energy distributions for selected quantum states of H and D formed in associative desorption reactions at a Au(111) surface. Using the principle of detailed balance, we compare our results to theory carried out at the same level of sophistication as was done for the reaction on copper.

Generation of ultra-short hydrogen atom pulses by bunch-compression photolysis.

Ultra-short light pulses enable many time-resolved studies in chemistry, especially when used in pump-probe experiments. However, most chemical events are not initiated by light, but rather by collisions. Time-resolved collisional experiments require ultra-short pulses of atoms and molecules--sadly, methods for producing such pulses are so far unknown.