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arXiv · 1710.00740

Ultrafast Molecular Transport on Carbon Surfaces: The Diffusion of Ammonia on Graphite

Anton Tamtögl·Marco Sacchi·Irene Calvo-Almazán·Mohamed Zbiri·Marek M. Koza·Wolfgang E. Ernst·Peter Fouquet
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Abstract

We present a combined experimental and theoretical study of the self-diffusion of ammonia on exfoliated graphite. Using neutron time-of-flight spectroscopy we are able to resolve the ultrafast diffusion process of adsorbed ammonia, NH$_3$, on graphite. Together with van der Waals corrected density functional theory calculations we show that the diffusion of NH$_3$ follows a hopping motion on a weakly corrugated potential energy surface with an activation energy of about 4 meV which is particularly low for this type of diffusive motion. The hopping motion includes further a significant number of long jumps and the diffusion constant of ammonia adsorbed on graphite is determined with $D=3.9 \cdot 10^{-8}~\mbox{m}^2 /\mbox{s}$ at 94 K.

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Anton Tamtögl, Marco Sacchi, Irene Calvo-Almazán, Mohamed Zbiri, Marek M. Koza, Wolfgang E. Ernst, Peter Fouquet. 2017-10-02. Ultrafast Molecular Transport on Carbon Surfaces: The Diffusion of Ammonia on Graphite. https://doi.org/10.1016/j.carbon.2017.09.104

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