Terahertz dynamics of electron–vibron coupling in single molecules with tunable electrostatic potential

Abstract

received: )Clarifying electronic and vibronic properties at individual molecule level provides key insights to future chemistry, nanoelectronics, and quantum information technologies. The single electron tunneling spectroscopy 1-4 has been used to study the charging/discharging process in single molecules. The obtained information was, however, mainly on static electronic properties, and access to their dynamical properties was very indirect. Here, we report on the terahertz (THz) spectroscopy of single fullerene molecules by using a single molecule transistor (SMT) geometry.From the time-domain THz autocorrelation measurements, we have obtained THz spectra associated with the THz-induced center-of-mass oscillation of the molecules. The observed peaks are finely split into two, reflecting the difference in the van der Waals potential profile experienced by the molecule on the metal surface when the number of electrons on the molecule fluctuates by one during the single electron tunneling process.Such an ultrahigh-sensitivity to the electronic/vibronic structures of a single molecule upon adding/removing a single electron has been

Direct Deposited Angstrom‐Scale Nanogap Electrodes with Macroscopically Measurable and Material‐Independent Capabilities for Various Applications

“…Sub‐5 nm NGEs have exhibited great superiority in many application fields, such as sensing, optical, molecular, and electronic devices . The gap separations decreasing from the nanometer down to the angstrom scale will revolutionize the existing nanogap‐related research and lead to valuable new physical phenomena such as nonlocal electromagnetic effects, quantum interference, nuclear spins, and electron tunneling, which can unlock the full potential of applications with high scientific and societal impact, including molecular electronics, quantum tunneling, plasmonic nano‐optics, and highly sensitive sequencing …”

“…Despite their importance, fabrication of sub‐5 nm NGEs remains a great technological challenge . Existing NGE‐manufacturing methods can be typically classified into two strategies: physical methods based on planar nanofabrication techniques and chemical methods based on noble metal nanoparticles. Most chemical methods are suitable for creating sub‐1 nm NGEs but limited to a relatively narrow range of applications owing to the contamination induced by linker molecules, the shell‐filled gaps, and/or the restrictions derived from metal nanoparticle size.…”

“…Most chemical methods are suitable for creating sub‐1 nm NGEs but limited to a relatively narrow range of applications owing to the contamination induced by linker molecules, the shell‐filled gaps, and/or the restrictions derived from metal nanoparticle size. Physical methods, including direct patterning techniques, breaking‐/cracking‐based methods, and controllable deposition, are fundamentally limited by the basic planar nanofabrication techniques. Particularly, direct patterning techniques variously suffer from high equipment costs, low throughput, and poor scalability to large sizes.…”

“…The breaking‐/cracking‐based methods are the most widely used but typically involve direct patterning techniques to predefine the wire pattern, a complex apparatus to induce external stimuli, or special materials (e.g., brittle films) to induce internal stress. Though breaking‐based methods can be used to produce sub‐1 nm NGEs, the intrinsic obstacles mentioned above result in discrete and material‐limited NGEs with the fractal facing electrode surface blocking the realization of large‐scale complex systems. Controllable deposition is relatively simple for large‐scale fabrication, while the formed NGEs typically face limitations derived from large gap width, problematic rough surfaces, the solution environment, or/and contaminations from the shadow‐mask fabrication process.…”

“…Compared with the existing NGE‐manufacturing methods, our technology presents several advances which will facilitate the exploitation of the existing NGE‐related applications and enable valuable new potential applications. First, the significant features in terms of facile fabrication, low cost, high efficiency, lithography‐ and etching‐free methods, lack of resist contaminations, and CMOS‐compatibility are naturally enabled by replacing the complicated patterning processes, which conventionally involve equipment‐intensive lithography and etching processing, with only a two‐step specially shadowed evaporation.…”