Electronics and Chemistry: Varying Single-Molecule Junction Conductance Using Chemical Substituents
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- 作者：Latha Venkataraman ; Young S. Park ; Adam C. Whalley ; Colin Nuckolls ; Mark S. Hybertsen ; Michael L. Steigerwald
- 刊名：Nano Letters
- 出版年：2007
- 出版时间：February 2007
- 年：2007
- 卷：7
- 期：2
- 页码：502 - 506
- 全文大小：1028K
- 年卷期：v.7,no.2(February 2007)
- ISSN：1530-6992
文摘
We measure the low bias conductance of a series of substituted benzene diamine molecules while breaking a gold point contact in a solutionof the molecules. Transport through these substituted benzenes is by means of nonresonant tunneling or superexchange, with the molecularjunction conductance depending on the alignment of the metal Fermi level to the closest molecular level. Electron-donating substituents,which drive the occupied molecular orbitals up, increase the junction conductance, while electron-withdrawing substituents have the oppositeeffect. Thus for the measured series, conductance varies inversely with the calculated ionization potential of the molecules. These resultsreveal that the occupied states are closest to the gold Fermi energy, indicating that the tunneling transport through these molecules isanalogous to hole tunneling through an insulating film.