Temperature Dependent Structural Phase Transition at the Perfluoropentacene/Ag(111) Interface
Monolayers of perfluoropentacene (PFP) on Ag(111) undergo a reversible structural transition from a crystalline (6 × 3) phase at low temperatures to a disordered phase at room temperature. Two-photon photoemission (2PPE) of the low temperature phase revealed a distinct signal of the first image-pote...
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Published in | Journal of physical chemistry. C Vol. 116; no. 2; pp. 1904 - 1911 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Columbus, OH
American Chemical Society
19.01.2012
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Subjects | |
Online Access | Get full text |
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Summary: | Monolayers of perfluoropentacene (PFP) on Ag(111) undergo a reversible structural transition from a crystalline (6 × 3) phase at low temperatures to a disordered phase at room temperature. Two-photon photoemission (2PPE) of the low temperature phase revealed a distinct signal of the first image-potential state (n = 1) of Ag(111), thus showing the presence of bare substrate regions between the crystalline PFP islands. At higher temperatures, the entire surface is covered by a disordered phase of diffusing molecules causing a complete suppression of the (n = 1) signal and the electron diffraction (LEED) pattern. X-ray absorption spectroscopy showed that neither a change of the weak chemical interaction nor a change of the molecular tilt angle occurs during this phase-transition. The quantitative analysis of the 2PPE signal and the LEED contrast yields a transition temperature of T C = 145 ± 5 K. The present experiment shows that desorption of excess multilayers leads to an effective coverage of less than a dense monolayer. |
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ISSN: | 1932-7447 1932-7455 |
DOI: | 10.1021/jp2094577 |