Bond Character of Thiophene on Ge(100): Effects of Coverage and Temperature

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• 作者：Seok Min Jeon ; Soon Jung Jung ; Hyeong-Do Kim ; Do Kyung Lim ; Hangil Lee ; Sehun Kim
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：November 2, 2006
• 年：2006
• 卷：110
• 期：43
• 页码：21728 - 21734
• 全文大小：576K
• 年卷期：v.110,no.43(November 2, 2006)
• ISSN：1520-5207

文摘

We have studied the adsorption and decomposition of thiophene (C₄H₄S) on Ge(100) using scanning tunnelingmicroscopy (STM), high-resolution core-level photoemission spectroscopy (HRPES), and density functionaltheory (DFT) calculation. Analysis of S 2p core-level spectra reveals three adsorption geometries, which weassign to a Ge-S dative bonding state, a [4 + 2] cycloaddition bonding state, and a decomposed bondingstate (desulfurization reaction product). Furthermore, we found that the number ratio of the three adsorptiongeometries depended on the molecular coverage and the annealing temperature. At low coverages, the kineticallyfavorable dative bonding state is initially formed at room temperature. As the molecular coverage increases,thermodynamically stable [4 + 2] cycloaddition reaction products are additionally produced. In addition, wefound that as the surface temperature increased, the [4 + 2] cycloaddition reaction product either possiblydesorbed as molecular thiophene or decomposed to form a metallocycle-like species (C₄H₄Ge₂) and a sulfide(Ge₂S). We systematically elucidate the changes in the bonding states of adsorbed thiophene on Ge(100)according to the thiophene coverage and annealing temperature.