科研之友
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摘要
Recently the complex polymorphism of naphthalene, C10H8, on Cu(111) was reported, with the conclusion that the polymorphism and thermodynamic behavior on that substrate are considerably more complex than what was known previously. Likewise, only two different commensurate structures of naphthalene on graphite are known so far. This study now identifies a total of six different highly ordered phases for this apparently simple molecule substrate system. All these phases are compiled in a detailed phase diagram, together with the information about the physical conditions needed to obtain them. As one remarkable turning point in the phase diagram, it is observed that the effective molecule molecule interaction changes from repulsive to attractive and vice versa upon temperature variation. Another reversible structural change occurs while the interaction is still attractive and the equilibrium distance of the molecules increases. We further show that not only the coverage and the temperature but also the specific route toward a certain structure is important to grow a desired phase. Based on our detailed structural analysis using distortion corrected low-energy electron diffraction, we provide the recipes for a controlled growth of C10H8 on graphite. We shed light on an unexpectedly complex phase diagram where in most cases a simple commensurate registry is not the preferred epitaxial relation.
- 出版日期2016-10-13
