Lonely adatoms in space

Abstract

There is a close relation between the problems of second layer nucleation in epitaxial crystal growth and chemical surface reactions, such as hydrogen recombination, on interstellar dust grains. In both cases standard rate equation analysis has been found to fail because the process takes place in a confined geometry. Using scaling arguments developed in the context of second layer nucleation, I present a simple derivation of the hydrogen recombination rate for small and large grains. I clarify the reasons for the failure of rate equations for small grains, and point out a logarithmic correction to the reaction rate when the reaction is limited by the desorption of hydrogen atoms (the second order reaction regime).

References in corpus (6)

• Master Equation for Hydrogen Recombination on Grain Surfaces
• Exact results for hydrogen recombination on dust grain surfaces
• Spatio-temporal distribution of nucleation events during crystal growth
• The process of irreversible nucleation in multilayer growth. I. Failure of the mean-field approach
• The process of irreversible nucleation in multilayer growth. II. Exact results in one and two dimensions
• Irreversible nucleation in molecular beam epitaxy: From theory to experiments

Cited by in corpus (11)

• Colloquium: Cluster growth on surfaces - densities, size distributions and morphologies
• Efficient simulations of gas-grain chemistry in interstellar clouds
• Molecular Hydrogen Formation on Low Temperature Surfaces in Temperature Programmed Desorption Experiments
• The sweeping rate in diffusion-mediated reactions on dust grain surfaces
• Efficient Stochastic Simulations of Complex Reaction Networks on Surfaces
• Accurate rate coefficients for models of interstellar gas-grain chemistry
• Diffusion-limited reactions and mortal random walkers in confined geometries
• Reaction Kinetics in a Tight Spot
• Diffusion-limited reactions on a two-dimensional lattice with binary disorder
• Coagulation kinetics beyond mean field theory using an optimised Poisson representation
• Diffusion-limited reactions on disordered surfaces with continuous distributions of binding energies