Bidentate Structures of Acetic Acid on Ge(100): The Role of Carboxyl Oxygen

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• 作者：Eunkyung Hwang ; Do Hwan Kim ; Yun Jeong Hwang ; Ansoon Kim ; Suklyun Hong ; Sehun Kim
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：April 26, 2007
• 年：2007
• 卷：111
• 期：16
• 页码：5941 - 5945
• 全文大小：435K
• 年卷期：v.111,no.16(April 26, 2007)
• ISSN：1932-7455

文摘

The adsorption structures of acetic acid on the Ge(100) surface at room temperature have been investigatedby using both scanning tunneling microscopy (STM) and density-functional theory (DFT) calculations. Theconversion of acetic acid to acetate on the Ge(100) surface occurs through dissociation of the O-H bond andthe formation of a Ge-O bond. The abstracted hydrogen atom saturates the dangling bond of the other Gedimer atom or diffuses to a neighboring dimer. Our STM results enable the identification of several adsorptionconfigurations, which arise from bonding involving either one oxygen atom (the monodentate structure) ortwo oxygen atoms (the bidentate structures). We observe two types of bidentate structures: the end-bridgedand on-top structures. The calculations show that the on-top structure is the most stable among many possibleadsorption products on the Ge(100) surface considered. Surfaces exposed to acetic acid are annealed toinvestigate the annealing effect. The end-bridged bidentate and monodentate structures are observed beforeannealing, while the on-top bidentate structure appears only after annealing. These behaviors are explainedin terms of reaction pathways obtained from theoretical calculations.