Molecular hydrogen formation on ice under interstellar conditions

The results of experiments on the formation of molecular hydrogen on low-density and high-density amorphous ice surfaces are analyzed using a rate equation model. The activation energy barriers for the relevant diffusion and desorption processes are obtained. The more porous morphology of the low-density ice gives rise to a broader spectrum of energy barriers compared to the high-density ice. Inserting these parameters into the rate equation model under steady-state conditions, we evaluate the production rate of molecular hydrogen on ice-coated interstellar dust grains.