Relating Energy Level Alignment and Amine-Linked Single Molecule Junction Conductance

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• 作者：M. Dell’ ; Angela ; G. Kladnik ; A. Cossaro ; A. Verdini ; M. Kamenetska ; I. Tamblyn ; S. Y. Quek ; J. B. Neaton ; D. Cvetko ; A. Morgante ; L. Venkataraman
• 刊名：Nano Letters
• 出版年：2010
• 出版时间：July 14, 2010
• 年：2010
• 卷：10
• 期：7
• 页码：2470-2474
• 全文大小：356K
• 年卷期：v.10,no.7(July 14, 2010)
• ISSN：1530-6992

文摘

Using photoemission spectroscopy, we determine the relationship between electronic energy level alignment at a metal−molecule interface and single-molecule junction transport data. We measure the position of the highest occupied molecular orbital (HOMO) relative to the Au metal Fermi level for three 1,4-benzenediamine derivatives on Au(111) and Au(110) with ultraviolet and resonant X-ray photoemission spectroscopy. We compare these results to scanning tunnelling microscope-based break-junction measurements of single molecule conductance and to first-principles calculations. We find that the energy difference between the HOMO and Fermi level for the three molecules adsorbed on Au(111) correlate well with changes in conductance and agree well with quasiparticle energies computed from first-principles calculations incorporating self-energy corrections. On the Au(110) that presents Au atoms with lower-coordination, critical in break-junction conductance measurements, we see that the HOMO level shifts further from the Fermi level. These results provide the first direct comparison of spectroscopic energy level alignment measurements with single molecule junction transport data.

Keywords:

Photoemission spectroscopy; metal−organic interface; density functional theory; single molecule conductance; benzenediamine