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Relating Energy Level Alignment and Amine-Linked Molecular Junction Conductance
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 Nano Letters, 10, 7, 2470-2474 (2010) This work establishes a direct connection between electronic energy level alignment at metal-molecule interfaces and single-molecule transport properties. The authors measured the position of the highest occupied molecular orbital (HOMO) relative to the gold Fermi level using ultraviolet and X-ray photoemission spectroscopy on benzenediamine derivatives, and correlated these measurements with scanning tunneling microscope break-junction conductance data. Strong correlations were found between HOMO-Fermi level energy differences and conductance across three molecular variants on gold surfaces. On Au(111), the measured energy alignments matched well with computed quasiparticle energies from first-principles calculations. However, on Au(110), the HOMO level shifted significantly further from the Fermi level, demonstrating that surface structure influences charge transport. This represents the first direct comparison of spectroscopic energy level alignment measurements with single molecule junction transport data, bridging spectroscopy and molecular electronics research. |
