Tunneling Decay Constant of Alkanedicarboxylic Acids: Different Dependence on the Metal Electrodes between Air and Electrochemistry

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• 作者：Ya-Hao Wang ; Ze-Wen Hong ; Yan-Yan Sun ; Dong-Fang Li ; Di Han ; Ju-Fang Zheng ; Zhen-Jiang Niu ; Xiao-Shun Zhou
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：August 14, 2014
• 年：2014
• 卷：118
• 期：32
• 页码：18756-18761
• 全文大小：383K
• ISSN：1932-7455

文摘

In this paper, the different tunneling decay constants 尾_N of alkanedicarboxylic acids depending on the metal electrodes in various surroundings are discussed. The conductance of alkanedicarboxylic acids (HOOC鈥?CH₂)_n鈥揅OOH, n = 2鈥?) contacting to Pd and Ag were systematically measured by the scanning tunneling microscopy (STM) break junction (STM-BJ) in air. A similar tunneling decay constant 尾_N of about 1 per 鈭扖H₂ was found for both metals, which might arise from the Fermi energy of electrodes pinning with the energy positions of molecular states under ambient atmosphere. However, the pinning effect can be destroyed by potential control in electrochemistry, and the 尾_N is determined by the alignment of the molecular energy levels relative to the Fermi energy level of the electrodes, which well explains the order of 尾_N,Pd < 尾_N,Ag < 尾_N,Cu in electrochemistry. The current work shows the important role of the surroundings in electron transport through molecular junctions.