Carlos Manzano’s research while affiliated with Agency for Science, Technology and Research (A*STAR) and other places

A tetrabenzo[a,c,j.h]phenazine molecule is functionning like a “2 input - 1 output” XOR Boolean logic gate using the quantum level repulsion effect of the Quantum Hamiltonian Computing approach. The logical inputs are performed using one aluminum atom per input. The logical output is measured by the dI/dV tunneling spectrum at +1.1 V low bias voltage. On an Au(111) surface, each Al atom is manipulated in and out of the molecule by scanning tunneling microscope molecular manipulations. This single molecule XOR gate functions without the need of cascading OR, AND and NAND gates inside its molecular structure.

The Kondo effect results from the interactions of the conduction electrons in a metal bulk with localized magnetic impurities. While adsorbed atop a metallic surface, the on-surface nanoscale version of this effect is observed when a single magnetic atom or a single magnetic molecule (SMM) is interacting with the conduction electrons. SMM are commonly organo-metallic complex incorporating transition metal atoms in different oxidation states. We demonstrate how a single non-magnetic neutral tetrabenzo[a,c,j,h]phenazine molecule can be on-surface coordinated with exactly two aluminum metal atoms (Al(III) oxidation state on the Au(111) surface) by low-temperature scanning tunneling microscope (LT-STM) single atom manipulation. It results a Kondo measurable localized molecular magnetic moment. This opens a new way to design SMM complex without the need of heavy transition metal atom and complex ligand to stabilize the molecular coordination sphere.

Using a low temperature scanning tunneling microscope (LT-UHV-STM), local electronic tunneling spectroscopy and differential conductance mapping are performed to investigate how by extending one phenyl more each branch of the conjugated board of a trinaphthylene starphene molecule, the corresponding longer trianthracene starphene new molecule is functioning like a NOR Boolean logic gate according to a Quantum Hamiltonian Computing (QHC) design. Here the STM tip is used to manipulate single Au atoms one at a time for contacting a trianthracene molecule. Each Au atom is acting like a classical digital input on the molecule encoding for a logical “0'' when the atom is not interacting with the trianthracene input branch and for a logical “1'' when interacting. The inputs are converted in quantum information inside the trianthracene molecule and the logical output status available on the output branch. QHC is demonstrated to be robust since quantum information transfer can be used on the long range along the trianthracene for the NOR logic gate to function properly as compared to the shorter trinaphthylene molecule.

A new disc-shaped highly symmetric C54H20 nanographene fragment, tetrabenzocircumpyrene, has been synthesized and characterized by scanning tunnelling microscopy, demonstrating the potential of this technique for identifying highly insoluble graphenic molecules.

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 functioning of the molecule gear. Rotation of the molecule gear is done step-by-step and totally under control. The fabrication of solid-state SiO2 nanogears with diameters ranging from 30 nm up to 1 μm and their manipulation using an atomic force microscope tip on a graphite surface is also presented. Ranging in sizes from few tens of nanometers up to submicron diameters, they are going to enable the transmission of mechanical motion from functional mechanical molecule machineries to larger submicron or micron-sized devices through series of solid-state gears and mechanical components compatible with the semiconductor and electronics industry technology.

a b s t r a c t Single gold adatoms were manipulated on a Au(1 1 1) surface with the tip of a scanning tunnelling microscope to contact selected peripheral p bonds of a single Coronene molecule. Tunnelling electron spectroscopy and differential conductance mapping of the Au–Coronene complexes show how Coron-ene's electronic ground state is shifted down in energy as the function of the number of interacting Au atoms, demonstrating that a Coronene molecule can function like a single molecule counter. The number of interacting atoms can be counted by simply following the linear energy downshift of Coronene's ground state. Ó 2013 Elsevier B.V. All rights reserved.

In this chapter is presented how the electron probability distributions of molecular states are imaged in real space using scanning tunneling microscopy. Differential tunneling conductance images of selected single molecules taken at voltages corresponding to resonances near the substrate Fermi level were found to be very close to their respective mono-electronic molecular orbitals. In contrast, high-order resonance states images were composed of molecular orbitals components from many states, even though those states lie in a lower energy range.

In this chapter experiments done to investigate the scanning tunneling microscope (STM) imaging at near field emission voltages of single Copper Phthalocyanine (CuPc) molecules deposited on Au(111) are presented. An imaging bias voltage range is explored exceeding the standard tunneling imaging conditions going from the threshold of the tunneling junction barrier up to −10.0 V. At this voltage regime current transmitted through the tip-molecule–substrate junction is made not only of tunneling electrons but also of electrons overcoming the tunneling barrier and behaving like free electrons. Our interpretation of the process, enabling the visualization of the electronic cloud of single organic molecules under these conditions, is presented.

Using a low temperature, ultrahigh vacuum scanning tunneling microscope (STM), dI/dV differential conductance maps were recorded at the tunneling resonance energies for a single Cu phthalocyanine molecule adsorbed on an Au(111) surface. We demonstrated that, contrary to the common assumption, such maps are not representative of the molecular orbital spatial expansion, but rather result from their complex superposition captured by the STM tip apex with a superposition weight which generally does not correspond to the native weight used in the standard Slater determinant basis set. Changes in the molecule conformation on the Au(111) surface further obscure the identification between dI/dV conductance maps and the native molecular orbital electronic probability distribution in space.