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Coverage-dependent disorder-to-order phase transformation of a uracil derivative on Ag(111)

Enache, M and Maggini, L and Llanes-Pallas, A and Jung, TA and Bonifazi, D and Stöhr, M (2014) Coverage-dependent disorder-to-order phase transformation of a uracil derivative on Ag(111). Journal of Physical Chemistry C, 118. pp. 15286-15291. ISSN 1932-7447

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The self-organization of an angular bis(uracil-ethynyl) benzene derivative is investigated on Ag(111) by means of scanning tunneling microscopy (STM) under ultrahigh vacuum (UHV) conditions. It is found-starting at low submonolayer coverage-that upon increasing the molecular coverage a disorder-to-order phase transformation occurs. Specifically, at low and intermediate molecular coverage a glassy phase consisting of one-dimensional (1D) chains and 2D aggregates is observed, while close to a first complete molecular layer, a well-ordered 2D close-packed phase is revealed. The main driving forces responsible for the structure formation are (i) the high self-complementarity of the uracil (U) moiety, resulting in U-U homopairs through 2-fold C=O⋯H-N H-bonds and (ii) the steric hindrance induced in the system by the alkyl chains. The delicate balance between the molecule-molecule and the molecule-substrate interactions leads to a complex phase behavior of the uracil derivative at the solid-vacuum interface. On the basis of this detailed study, we present a qualitative understanding of the peculiar phase behavior of the system. © 2014 American Chemical Society.

Item Type: Article
Divisions: Div E > Manufacturing Systems
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:23
Last Modified: 22 May 2018 07:22