A means for controlling single-molecule switches by engineering their design and surrounding environment has been developed by a research team led by scientists at Penn State, Rice University, and the University of Oregon. The research demonstrates that single-molecule switches can be tailored to respond in predictable and stable ways, depending on the direction of the electric field applied to them--while some switches were engineered to turn on, others were engineered to turn off in response to the same applied electric field. The discovery, which is an essential step in the emerging field of molecular electronics, could further the development of nano-components--as small as molecules or atoms--for use in future generations of computers and other electronic devices.
Credit: Lewis et al.
Sequential STM images of FAPPB/R1ATC9 obtained at alternating sample biases of +1.0 and -1.0 V. The majority of the FAPPB molecules (apparent protrusions, displayed as bright spots) switch conductance states between OFF at +1.0 V and ON at -1.0 V sample bias. The red and green boxes follow one FAPPB molecule that exhibits this bias dependence. Imaging conditions: 4000 ‰ × 4000 ‰, I = 2 pA.
A paper describing the research results, titled "Molecular Engineering of the Polarity and Interactions of Molecular Electronic Switches," will be published in the Journal of the American Chemical Society on 21 December 2005. "This research confirms our hypothesis of how single-molecule switches work," says Penn State Professor of Chemistry and Physics Paul S. Weiss, whose lab tested the molecules. "Molecular switches eventually may become integrated into real electronics, but not until after someone discovers a way to wire them." In addition to Weiss, the research team includes Penelopie Lewis of Penn State, who now is at Columbia University; James Tour and Francisco Maya at Rice University; and James Hutchison and Christina Inman at the University of Oregon.
The research is the latest achievement in the teams ongoing studies of a family of stiff, stringy molecules known as as OPEs--oligo phenylene-ethynylenes--which the scientists have tailored in a number of ways to have a variety of physical, chemical, and electronic characteristics. The potential for using these OPE molecules as switches had been limited by their troublesome tendency to turn on and off at random, but Weiss and his colleagues recently discovered a way to reduce this random switching. In their current research, the scientists demonstrated, with a number of definitive experiments, how and why it is possible to control these molecular switches.
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22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
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Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
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Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
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For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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