Role of anisotropic electronic friction in laser-driven hydrogen recombination on copper

TL;DR

This study uses machine learning simulations to compare isotropic and anisotropic electronic friction effects in laser-driven hydrogen reactions on copper, revealing anisotropic friction's role in energy transfer rates but not in final energy distributions.

Contribution

It introduces a machine-learning framework to distinguish the effects of anisotropic versus isotropic electronic friction in surface reactions.

Findings

Anisotropic friction influences energy transfer rates and reaction fluence dependence.

Final energy distributions are mainly determined by the potential energy landscape.

Anisotropic friction has little impact on the final vibrational and rotational energies.

Abstract

Ultrafast light-driven chemical dynamics at surfaces are governed by energy transfer from excited electrons to vibrational degrees of freedom. When this nonadiabatic energy transfer is anisotropic, it can lead to dynamical steering effects that affect reaction probabilities or non-thermal final energy distributions in molecules. Here, we use a machine-learning-enabled simulation framework to compare isotropic and anisotropic models of electronic friction during laser-driven hydrogen evolution on the (111) facet of copper. While anisotropic friction strongly determines the rate of energy transfer into the adsorbate and the fluence dependence of reaction probabilities, it has little effect on final translational, vibrational and rotational energy distributions as these are mainly governed by the potential energy landscape at the barrier.