Peng, Hao HowardHao HowardPengLin, Geng MinGeng MinLinLin, Chih HsunChih HsunLinCHUN-HSIEN CHENWang, Tsai HuiTsai HuiWangHSIAO-HAN CHAOHo, Ching HwaChing HwaHoHsu, Hsiu FuHsiu FuHsu2019-10-022019-10-022019-01-0119327447https://scholars.lib.ntu.edu.tw/handle/123456789/425700© Copyright 2019 American Chemical Society. Charge transport across molecular junctions can be described by G = Gcontactexp(-βL), envisioned as sequential propagation through electrode-molecule contacts (Gcontact) and the molecular backbone (exp(-βL)). How Gcontact and exp(-βL) are modulated by the chemical potentials of the electrodes (EF), although essential, remains relatively unexplored because EF is typically driven by the applied Vbias and hence limited to a small range in that a large Vbias introduces complicated transport pathways. Herein, the interrelated EF and Vbias are electrochemically disentangled by fixing Vbias at a small value while potentiostatically positioning the electrode EF in a 1.5 V range. The results show that EF affects Gcontact more pronouncedly than the molecular backbone. For the covalently anchored acetylene-electrode (CC-Au) junctions, the energy level of the frontier molecular orbital (EFMO) is found to shift nonlinearly as EF changes; |EFMO-EF| is independent of EF in the range of-0.25 to 0.00 V (vs EAg/AgCl) and is narrowed by -32% at 0.00-0.75 V. These findings are elucidated by the refined Simmons model, Newns-Anderson model, and single-level Breit-Wigner formula and quantitatively shed light on the influence of electrodes on the molecular orbitals (viz., the self-energy, ς).journal article10.1021/acs.jpcc.9b059272-s2.0-85072555274https://api.elsevier.com/content/abstract/scopus_id/85072555274