Person: Golovchenko, Jene
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Golovchenko
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Jene
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Golovchenko, Jene
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Publication Ion selectivity of graphene nanopores(Nature Publishing Group, 2016) Rollings, Ryan C.; Kuan, Aaron; Golovchenko, JeneAs population growth continues to outpace development of water infrastructure in many countries, desalination (the removal of salts from seawater) at high energy efficiency will likely become a vital source of fresh water. Due to its atomic thinness combined with its mechanical strength, porous graphene may be particularly well-suited for electrodialysis desalination, in which ions are removed under an electric field via ion-selective pores. Here, we show that single graphene nanopores preferentially permit the passage of K+ cations over Cl− anions with selectivity ratios of over 100 and conduct monovalent cations up to 5 times more rapidly than divalent cations. Surprisingly, the observed K+/Cl− selectivity persists in pores even as large as about 20 nm in diameter, suggesting that high throughput, highly selective graphene electrodialysis membranes can be fabricated without the need for subnanometer control over pore size.Publication Escape of DNA from a Weakly Biased Thin Nanopore: Experimental Evidence for a Universal Diffusive Behavior(American Physical Society (APS), 2013) Hoogerheide, David Paul; Albertorio, Fernando; Golovchenko, JeneWe report experimental escape time distributions of double-stranded DNA molecules initially threaded halfway through a thin solid-state nanopore. We find a universal behavior of the escape time distributions consistent with a one-dimensional first passage formulation notwithstanding the geometry of the experiment and the potential role of complex molecule-liquid-pore interactions. Diffusion constants that depend on the molecule length and pore size are determined. Also discussed are the practical implications of long time diffusive molecule trapping in the nanopore.Publication Pressure-Controlled Motion of Single Polymers through Solid-State Nanopores(American Chemical Society (ACS), 2013) Lu, Bo; Hoogerheide, David Paul; Zhao, Qing; Zhang, Hengbin; Tang, Zhipeng; Yu, Dapeng; Golovchenko, JeneVoltage-biased solid-state nanopores are well established in their ability to detect and characterize single polymers, such as DNA, in electrolytes. The addition of a pressure gradient across the nanopore yields a second molecular driving force that provides new freedom for studying molecules in nanopores. In this work, we show that opposing pressure and voltage bias enables nanopores to detect and resolve very short DNA molecules, as well as to detect near-neutral polymers.Publication Probing Nanotube-Nanopore Interactions(American Physical Society (APS), 2005) King, G. M.; Golovchenko, JeneWe demonstrate a new nanoscale system consisting of a nanotube threaded through a nanopore in aqueous solution. Its electrical and mechanical properties are sensitive to experimentally controllable conformational changes on sub-Angstrom length scales. Ionic current transport through a nanopore is significantly suppressed by the threading nanotube and the mechanical interactions between the nanotube and pore are accounted for by a folding geometry. The experiments provide first measurements of the longitudinal resolution and metrology of a solid-state nanopore “microscope.” This new nanostructure provides a means to study molecule-nanotube interactions in conducting ionic solutions as well as geometrical and surface properties of nanopores and nanotubes.Publication Comment on “Low-temperature homoepitaxial growth on high-miscut Si(111) mediated by thin overlayers of Pb” [Appl. Phys. Lett. 75, 2954 (1999)](AIP Publishing, 2000) Evans, P. G.; Dubon, O. D.; Chervinsky, John; Spaepen, Frans; Golovchenko, JenePublication Three-stage lattice relaxation of Ge islands on Si(111) measured by tunneling microscopy(AIP Publishing, 1995) Theiss, Silva K.; Chen, D. M.; Golovchenko, JeneWe use the tunneling microscope to measure the surface lattice spacing of Ge islands grown on Si(111) as a function of their height. It changes in three stages: (I) (0–50 layers tall) Rapid relaxation from near the bulk Si value, at the end of which the lattice spacing atop some of the islands exceeds that of bulk Ge. (II) (50–80 layers) Rapid decrease in surface lattice spacing, to nearly 2% below the bulk Ge value. (III) (≳80 layers) Gradual relaxation to the bulk value. Additional observations of dislocations and analysis of island widths are used to explain this behavior.Publication Liquid-metal-mediated homoepitaxial film growth of Ge at low temperature(AIP Publishing, 1991) Xiong, Fulin; Ganz, Eric; Loeser, A. G.; Golovchenko, Jene; Spaepen, FransWe demonstrate liquid‐metal‐mediatedhomoepitaxialcrystal growth of Ge on Ge(111) at temperatures in the range of 400–450 °C. Crystal growth proceeds by diffusion of Ge through a liquid layer, followed by precipitation onto the substrate by the vapor‐liquid‐solid mechanism. The liquid‐metal phase at the interface is a Au‐Ge alloy formed by initial deposition of a thin Au layer above the eutectic temperature. Ge vapor is provided by a molecular‐beam evaporator. The resulting films revealed high‐crystalline quality by in situ high‐energy ion scattering and channeling analysis and ex situ by cross‐sectional transmission electron microscopy.Publication Adatom registry on Si(111)-(√3 × √3 )R30°-B(American Physical Society (APS), 1990) Bedrossian, P.; Mortensen, K.; Chen, D. M.; Golovchenko, JeneWe have used tunneling microscopy to determine the binding site of adatoms on Si(111)-(√3 × √3 )R30° stabilized by surface boron doping. The adatoms are found to occupy the T4 binding site, regardless of either the local dopant concentration or the presence or absence of a substitutional boron atom directly underneath individual adatoms.Publication Direct measurement of crystal surface stress(American Physical Society (APS), 1990) Martinez, Robert; Augustyniak, Walter; Golovchenko, JeneWe have measured surface stresses on clean Si(111) 7×7 by comparing this surface to a reference surface on which gallium atoms are adsorbed under UHV conditions. Stresses are determined by optically measuring the macroscopic strain induced in thin samples. We find a surface stress of 2.37 eV/(1×1 cell) for Si(111) 7×7, and a stress in the range 0.90–1.09 eV/(1×1 cell) for the Si(Ga) (111) superlattice associated with one monolayer Ga coverage. Comparison with theory suggests that our technique will be a powerful tool to measure equilibrium stresses in atomically clean surfaces.Publication Nanometer-thin solid-state nanopores by cold ion beam sculpting(AIP Publishing, 2012) Kuan, Aaron; Golovchenko, JeneRecent work on protein nanopores indicates that single molecule characterization (including DNA sequencing) is possible when the length of the nanopore constriction is about a nanometer. Solid-state nanopores offer advantages in stability and tunability, but a scalable method for creating nanometer-thin solid-state pores has yet to be demonstrated. Here we demonstrate that solid-state nanopores with nanometer-thin constrictions can be produced by “cold ion beam sculpting,” an original method that is broadly applicable to many materials, is easily scalable, and requires only modest instrumentation.