From Benzenetrithiolate Self-Assembly to Copper Sulfide Adlayers on Cu(111): Temperature-Induced Irreversible and Reversible Phase Transitions

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• 作者：Thomas Sirtl ; Matthias Lischka ; Johanna Eichhorn ; Atena Rastgoo-Lahrood ; Thomas Strunskus ; Wolfgang M. Heckl ; Markus Lackinger
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：February 20, 2014
• 年：2014
• 卷：118
• 期：7
• 页码：3590-3598
• 全文大小：499K
• ISSN：1932-7455

文摘

Self-assembly and thermally activated surface chemistry of 1,3,5-benzenetrithiol (BTT) on Cu(111) are studied under ultrahigh vacuum (UHV) conditions by different complementary surface sensitive techniques. Low-energy electron diffraction (LEED) patterns acquired at room temperature and during subsequent heating reveal irreversible phase transitions between in total four different long-range-ordered phases termed 伪-phase to 未-phase. X-ray photoelectron spectroscopy (XPS) of the different phases facilitates the identification of major chemical changes for the first phase transition from 伪- to 尾-phase, whereas in the succeeding phase transitions, no significant chemical shifts are observed anymore. The structural characterization of each phase is carried out by high-resolution scanning tunneling microscopy (STM), and adsorption geometries of the phenyl rings are derived from C 1s near-edge X-ray absorption fine structure (NEXAFS). The combination of the results from this array of experimental techniques leads to a consistent picture of the various phases and underlying processes. Upon room-temperature deposition, BTT fully deprotonates and planar-adsorbed molecules self-assemble into an ordered monolayer. With a temperature onset of 300 K, the carbon鈥搒ulfur bonds start dissociating. Sulfur forms a copper sulfide superstructure, whereas the organic remainders form disordered structures. Further heating converts an initial metastable and rarely observed (鈭? 脳 鈭?)R 卤 30掳 copper sulfide superstructure into the more stable and well-known (鈭? 脳 鈭?)R 卤 19.1掳 polymorph.