Electronics and chemistry: Varying single-molecule junction conductance using chemical substituents
Electronics and chemistry: Varying single-molecule junction conductance using chemical substituents
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DOI：
10.1021/nl062923j
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发表时间：
2007-02-01
期刊：
影响因子：
10.8
通讯作者：
Steigerwald, Michael L.
中科院分区：
文献类型：
--
作者：
Venkataraman, Latha;Park, Young S.;Steigerwald, Michael L.
我们测量了一系列取代苯二胺分子的低偏压电导，同时打破了分子溶液中的金点接触。通过这些取代苯的传输是通过非共振隧道效应或超交换实现的，分子结电导取决于金属费米能级与最接近分子能级的排列。供电子取代基驱动占据的分子轨道向上，增加结电导，而吸电子取代基则具有相反的效果。因此，对于测量的系列，电导与计算的分子电离势成反比变化。这些结果表明，占据态最接近金费米能量，表明通过这些分子的隧道传输类似于通过绝缘膜的空穴隧道传输。
We measure the low bias conductance of a series of substituted benzene diamine molecules while breaking a gold point contact in a solution of the molecules. Transport through these substituted benzenes is by means of nonresonant tunneling or superexchange, with the molecular junction 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 opposite effect. Thus for the measured series, conductance varies inversely with the calculated ionization potential of the molecules. These results reveal that the occupied states are closest to the gold Fermi energy, indicating that the tunneling transport through these molecules is analogous to hole tunneling through an insulating film.