Ballistic Diffusion in Polyaromatic Hydrocarbons on Graphite

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• 作者：Irene Calvo-AlmazánMarco Sacchi ; Anton Tamtögl ; Emanuel Bahn ; Marek M. Koza ; Salvador Miret-Artés ; Peter Fouquet
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：December 15, 2016
• 年：2016
• 卷：7
• 期：24
• 页码：5285-5290
• 全文大小：442K
• ISSN：1948-7185

文摘

This work presents an experimental picture of molecular ballistic diffusion on a surface, a process that is difficult to pinpoint because it generally occurs on very short length scales. By combining neutron time-of-flight data with molecular dynamics simulations and density functional theory calculations, we provide a complete description of the ballistic translations and rotations of a polyaromatic hydrocarbon (PAH) adsorbed on the basal plane of graphite. Pyrene, C₁₆H₁₀, adsorbed on graphite is a unique system, where at relative surface coverages of about 10–20% its mean free path matches the experimentally accessible time/space scale of neutron time-of-flight spectroscopy (IN6 at the Institut Laue-Langevin). The comparison between the diffusive behavior of large and small PAHs such as pyrene and benzene adsorbed on graphite brings a strong experimental indication that the interaction between molecules is the dominating mechanism in the surface diffusion of polyaromatic hydrocarbons adsorbed on graphite.