Observation of orbital gate modulation in molecular junctions

We report the observation of direct gate modulation of molecular orbitals in solid-state molecular junctions where transport current is controlled by an external gate. Resonant-enhanced coupling to the nearest molecular orbital is revealed by electron tunneling spectroscopy, demonstrating direct molecular orbital gating in an electronic device. We contrast molecular structures that have near-resonant coupling to ones that have far-from-resonant coupling. We show this using a multiprobe approach combining a variety of transport techniques that elucidates the transport mechanisms and electronic structure of molecular junctions.