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Publications (43)
Complex atomic-scale circuits designed in classical, semi-classical and Quantum Hamiltonian Computing approaches using multi-atomic wires interconnects and Au(111) metallic nano-pads contacts discussed in Chapter “The Design of a Surface Atomic Scale Logic Gate with Molecular Latch Inputs” have been investigated to go forward for reaching compact a...
Two-input/one-output atomic scale Boolean logic gates are presented which are supposed to be atom by atom STM constructed on an Si(100)H-passivated surface. For those relatively simple logic gates, semi-classical and quantum Hamiltonian computing (QHC) architectures are compared showing how the QHC design avoids long atomic scale wiring compulsory...
To control the logical inputs in a surface atomic scale circuit, we introduce the concept of molecule-latch. The switching of certain molecules on a surface can be used to control the conductance of a very simple atomic scale interferometer that can be constructed atom by atom on an Si(100)H surface by STM atomic manipulation. Among the possible su...
Molecular-scale electronics is mainly concerned by understanding charge transport through individual molecules. A key issue here is the charge transport capability through a single-typically linear-molecule, characterized by the current decay with increasing length. To improve the conductance of individual polymers, molecular design often either in...
The first experimental demonstration of a controllable rotating molecule gear is presented. A scanning tunneling microscope (STM) is used to construct, manipulate, and observe the rotation of the molecule gear. The appropriate combination of molecule design, molecule manipulation protocol, and surface atomic structure selection leads to the functio...
The mechanical switching of a single pentacene molecule chemisorbed in a planar configuration along a dimer row of the Si(100)-(2 × 1) surface was performed experimentally using the tip apex of a scanning tunneling microscope. The mechanical switching reaction path was identified theoretically on the ground state potential energy surface of the pen...
Electron transport through atomic-scale circuits made of dangling-bond (DB) wires is discussed using the N-ESQC technique taking also into account the contacting nanopads on the circuits. The band structure of the Si(001)-(2x1):H surface is analyzed together with the ones with infinite dangling-bond wires. The exponential decay in the conductance w...
Scanning tunneling microscopy is a very suitable instrument for the local probing and spectroscopic characterization of individual molecules, in our case narrow graphene nanoribbons. The electronic properties of a graphene nanoribbon can be controlled by its edge structure and width. Bottom-up approaches like on-surface synthesis allow the formatio...
Atomic-scale dangling-bond Boolean logic gates with two inputs and one output are designed on a Si(001)-(2x1):H surface. The dangling-bond logic gates are connected to the macroscopic scale by metallic nano-electrodes physisorbed on the Si(100)-(2x1):H surface. The logic inputs are provided by saturating and unsaturating surface Si dangling bonds,...
The design of artificial molecular machines often takes inspiration from macroscopic machines. However, the parallels between the two systems are often only superficial, because most molecular machines are governed by quantum processes. Previously, rotary molecular motors powered by light and chemical energy have been developed. In electrically dri...
Graphene nanoribbons could potentially be used to create molecular wires with tailored conductance properties. However, understanding charge transport through a single molecule requires length-dependent conductance measurements and a systematic variation of the electrode potentials relative to the electronic states of the molecule. Here, we show th...
A new class of double-wheel molecules is manipulated on a Au(111) surface by the tip of a scanning tunneling microscope (STM) at low temperature. The double-wheel molecule consists of two subphthalocyanine wheels connected by a central rotation carbon axis. Each of the subphthalocyanine wheels has a nitrogen tag to monitor its intramolecular rollin...
The future's wheel: A new class of wheels, based on subphthalocyanine fragments, for future incorporation in functional nanovehicles is reported (see figure). The syntheses of a symmetric wheel, a nitrogen-tagged wheel, and their ethynyl-bridged homodimers are presented. Theoretical calculations and STM imaging demonstrate the advantage of a bowl-s...
Atomic-scale Boolean logic gates (LGs) with two inputs and one output (i.e. OR, NOR, AND, NAND) were designed on a Si(100)-(2 × 1)-H surface and connected to the macroscopic scale by metallic nano-pads physisorbed on the Si(100)-(2 × 1)-H surface. The logic inputs are provided by saturating and unsaturating two surface Si dangling bonds, which can,...
The detailed fabrication and manipulations of solid state nano gears up
to 350 nm in diameter is reported. Atomic force microscopy (AFM) and
ultra high vacuum (UHV) scanning tunneling microscopy (STM) are used to
maneuver the gears. The aim is to bridge the gap between the current
solid state gears and the now available nanoscale gears. As in many...
A process is presented to fabricate solid-state nano-gears down to a 60 nm outer diameter with six teeth, where the 350 nm diameter ones already have 24 teeth. The small gears are free to move on a polycrystalline gold surface. The gears can be manipulated one by one, using an atomic force microscope (AFM) tip, to construct a train of gears where m...
A logic gate has been implemented in a single trinaphthylene molecule. Each logical input controls the position of a surface Au atom that is brought closer or further away from the end of one of the naphthyl branch. Each Au atom carries 1 bit of information and is able to deform nonlocally and to shift in energy the molecular electronic states of t...
Electron transport calculations were carried out for three terminal OR logic gates
constructed either with a single molecule or with a surface dangling bond circuit
interconnected on a Si(100)H surface. The corresponding multi-electrode multi-channel
scattering matrix (where the central three terminal junction OR gate is the scattering
center) was...
Quantum states of a trinaphthylene molecule were manipulated by putting its naphthyl branches in contact with single Au atoms. One Au atom carries 1-bit of classical information input that is converted into quantum information throughout the molecule. The Au-trinaphthylene electronic interactions give rise to measurable energy shifts of the molecul...
The adsorption of individual [11]anthrahelicene molecules and their self-assembly into monolayer islands on an InSb(001) c(8×2) reconstructed surface is studied with low-temperature scanning probe microscopy. A racemic mixture is deposited on atomically flat terraces of InSb at room temperature. At lower coverage, the molecules tend to decorate ato...
The mechanical response of ultrathin NaCl crystallites of nanometer dimensions upon manipulation with the tip of a scanning tunneling microscope (STM) is investigated, expanding STM manipulation to various nanostructuring modes of inorganic materials as cutting, moving, and cracking. In the light of theoretical calculations, our results reveal that...
One prerequisite for the realization of molecular electronics is a fundamental understanding of charge transport through single molecules. We have conducted experiments with a low temperature scanning tunneling microscope (STM) that allow to measure currents going through a single long molecular wire as a continuous function of the distance between...
The adsorption of indigo molecules on Cu(111) was investigated by low temperature (5 K) scanning tunneling microscopy from the isolated single molecule regime to one monolayer. Structural optimization and image calculations demonstrate that the molecules are in a physisorbed state. Because of the reduced symmetry at the surface, single molecules ac...
At the exact contacting distance of a CO molecule inserted in the tunnel junction between a Cu(311) surface and an STM tip, it is demonstrated that the calculated conductance of a single CO is smaller (G=6×10−4Go with Go=2e2/h) than the corresponding vacuum junction conductance. This is not due to a destructive interference between tunnel channels...
Diese Arbeit wurde vom EU-Projekt “pico inside”, dem Förderprogramm “Functional materials at the nanoscale” (FU Berlin) und der DFG (SFB 658) finanziell gefördert. Wir danken Christian Roth für die technische Unterstützung, und L.G. dankt Gerhard Meyer für hilfreiche Diskussionen.
Totally wired: A particular molecular adsorption geometry can be prepared by adsorbing single conjugated polyfluorene chains partially on a clean Au(111) surface and partially on a thin crystalline NaCl film, thus connecting metallic and insulating surface areas. This configuration allows the electronic characterization of one and the same molecula...
Gears are microfabricated down to diameters of a few micrometres. Natural macromolecular motors, of tens of nanometres in diameter, also show gear effects. At a smaller scale, the random rotation of a single-molecule rotor encaged in a molecular stator has been observed, demonstrating that a single molecule can be rotated with the tip of a scanning...
The development of electronic devices at the single-molecule scale requires detailed understanding of charge transport through
individual molecular wires. To characterize the electrical conductance, it is necessary to vary the length of a single molecular
wire, contacted to two electrodes, in a controlled way. Such studies usually determine the con...
Decoupling the electronic properties of a molecule from a substrate is of crucial importance for the development of single-molecule electronics. This is achieved here by adsorbing pentacene molecules at low temperature on a hydrogenated Si(100) surface (12 K). The low temperature (5 K) scanning tunneling microscope (STM) topography of the single pe...
The adsorption and switching behavior of 3,3′,5,5′-tetra-tert-butylazobenzene (meta-TBA) are investigated by low-temperature scanning tunneling microscopy on three different metal substrates: Au(111), Cu(111), and Au(100). The trans state is the most stable configuration after adsorption, displaying similar appearances in the STM images, independen...
The adsorption of polyacene molecules on a H-terminated Si(0 0 1)-2 × 1 surface where a few hydrogen atoms have been extracted is presented using the semi-empirical ASED+ method. To scale up the qualitative ASED+ method, the adsorption of benzene and pentacene on a clean silicon surface is first compared with DFT calculations together with their ad...
A Morse manipulator like molecule able to modulate the electronic standing wave pattern of metallic Shockley surface states is presented. Its design is based on a molecular arm holding a phenyl whose distance to the metal surface is controlled by the tip apex of an STM. The standing wave patterns are calculated using an extension of the N-ESQC tech...
The sublimation of molecules under ultra-high vacuum conditions becomes critical with increasing molecular complexity as thermal fragmentation comes into play. In this case, scanning tunneling microscopy experiments of large molecules commonly focus on the small portion of the surface displaying intact molecules. In this work, we shed light on the...
To describe the adsorption of large organic molecules on metal surfaces, to calculate the corresponding diffusion and rotation barriers, the semi-empirical mono-electronic Hamiltonian of the ASED molecular orbital method have been completed to take into account three body interaction terms. The full re-parametrization of this ASED+ version of ASED...
The decomposition of acetylene on a Rh(100) single crystal was studied by a combination of experimental techniques [static secondary ion mass spectrometry (SSIMS), temperature-programmed desorption (TPD), and low-energy electron diffraction (LEED)] to gain insight into the reaction pathway and the nature of the reaction intermediates. The experimen...
Density functional theory has been used to gain molecular understanding of various catalytic processes involving N species on Rh(111). These include CN, N2, and HCN formation and N2O decomposition. Our calculations substantiate the conclusion that, starting from chemisorbed C and N atomic species, CN formation is preferred over N2 formation, becaus...
Periodic DFT calculations have been performed to investigate the adsorption, activation, and reactivity of N2O on a Rh(111) surface. Several adsorption modes in a narrow range of energies have been found. The most stable situation corresponds to a weak bonding (0.39 eV) via the N-terminal atom on top of a Rh atom, with the lineal N2O molecule situa...
The low coverage adsorption modes of CN on Pt(1 1 1) have been studied by means of density functional theory and both cluster and slab models; geometry, adsorption energy and vibrational frequencies have been computed. The most favourable adsorption mode is C-down on top, with the CN axis perpendicular to the surface. Hollow sites are also stable m...
The low coverage adsorption modes of CN on Pt(1 1 1) have been studied by means of density functional theory and both cluster and slab models; geometry, adsorption energy and vibrational frequencies have been computed. The most favourable adsorption mode is C-down on top, with the CN axis perpendicular to the surface. Hollow sites are also stable m...
Cyanide formation and nitrogen recombination on Rh(1 1 1) have been studied using density functional theory. CN can interact with the surface via several adsorption modes, all of them within a very narrow range of adsorption energies. CN can be regarded as a highly mobile species on the surface, and dissociation is associated with a considerable lo...
A comparative study of the chemisorption of the isoelectronic species CO and CN− on Rh, Ni, Pd and Pt(1 1 1) surfaces has been performed using the cluster model approach and the density functional theory. The CO bond is weakened whereas the CN− one is strengthened upon chemisorption in agreement with experimental evidence based on shifts to lower o...
