Ultrafast molecular transport on carbon surfaces: The diffusion of ammonia on graphite

Anton Tamtögl, Marco Sacchi, Irene Calvo-Almazán, M. Zbiri, Marek M. Koza, W.E. Ernst, Peter Fouquet

Research output: Contribution to journalArticleResearchpeer-review


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, NH3, on graphite. Together with van der Waals corrected density functional theory calculations we show that the diffusion of NH3 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⋅10−8m2/s at 94 K.

Original languageEnglish
Pages (from-to)23-30
Number of pages8
Publication statusPublished - 1 Jan 2018



  • Adsorption
  • Ammonia
  • DFT
  • Diffusion
  • Graphite
  • Neutron scattering

Fields of Expertise

  • Advanced Materials Science

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