As a conductor, graphene lets electrons zip too fasthere no controlling or stopping themhile boron nitride nanotubes are
so insulating that electrons are rebuffed like an overeager dog hitting the patio door. But together, these two materials make a workable digital switch
which is the basis for controlling electrons in computers, phones, medical equipment and other electronics.
or differences in how much energy it takes to excite an electron in the material. hen we put them together,
you form a band gap mismatchhat creates a so-called otential barrierthat stops electrons. The band gap mismatch results from the materialsstructure:
caused by the difference in electron movement as currents move next to and past the hairlike boron nitride nanotubes.
These points of contact between the materialsalled heterojunctionsre what make the digital on/off switch possible. magine the electrons are like cars driving across a smooth track,
With their aligned atoms, the graphene-nanotube digital switches could avoid the issues of electron scattering. ou want to control the direction of the electrons,
slows down and redirects electrons. his is difficult in high speed environments, and the electron scattering reduces the number and speed of electrons.
Much like an arcade enthusiast, Yap says he and his team will continue trying to find ways to outsmart
or change the pinball setup of graphene to minimize electron scattering. And one day all their tweaks could make for faster computersnd digital pinball gamesor the rest of us t
and electrons in metal surfaces to develop novel components for optical data transmission between chips. The project is funded under the 7th Research Framework Programme of the European union
As recently published in AIP Applied Physics Letters("Patterned graphene ablation and two-photon functionalization by picosecond laser pulses in ambient conditions),
#Integration of quantum dots and photonic crystals produce brighter, more efficient light Recently, quantum dots (QDS) ano-sized semiconductor particles that produce bright, sharp,
"For this research, the team used the Center for Nanoscale Materials as well as beamline 12-ID-C of the Advanced Photon Source, both DOE Office of Science User Facilities.
Curtiss said the Advanced Photon Source allowed the scientists to observe ultralow loadings of their small clusters, down to a few nanograms,
In addition, as an actual needle application, we demonstrated fluorescenctce particle depth injection into the brain in vivo,
because they have the ability to capture individual photons of light. When fashioned into certain shapes, with specifically patterned surfaces,
they can channel photons along their surface, focusing their energy into a tight spot. When the material is a metal,
or the development of silicon computing chips that process data communicated by photons of light instead of electricity.
because they are relatively cheap and easy to fashion into the right shapes needed to channel photons the right way.
"The cloud of free-moving electrons around a metal that carries an electrical current can also absorb passing photons.
but their electrons absorb fewer passing photons.""While this extremely localised and directed heating effect has been put to some good uses like targeting cancerous cells to kill them,
First, the control voltage mediates how electrons pass through a boundary that can flip from an ohmic (current flows in both directions) to a Schottky (current flows one way) contact and back.
"We transferred electrons from the dopant-potassium-to the surface of the black phosphorus, which confined the electrons
and allowed us to manipulate this state. Potassium produces a strong electrical field which is required what we to tune the size of the band gap."
"This process of transferring electrons is known as doping and induced a giant Stark effect, which tuned the band gap allowing the valence
Now, researchers from the University of Bristol in the UK and Nippon Telegraph and Telephone (NTT) in Japan, have pulled off the same feat for light in the quantum world by developing an optical chip that can process photons in an infinite number
This result shows a step change for experiments with photons and what the future looks like for quantum technologies.
Now anybody can run their own experiments with photons, much like they operate any other piece of software on a computer.
The conjecture is that this arises from an avalanche of electrons from the top surface of the film to the bottom,
where the electrons are confined near the substrate. This shift of electric charge occurs as the manganese atomic layers form atomically charged capacitors leading to the build up of an electric field, known as polar catastrophe
Of particular importance are new materials that conduct electricity by using missing electrons, otherwise known as"holes."
Although electron conducting (n-type) TCOS are presently in use in many devices, their hole-conducting (p-type) counterparts have not been commercialized as candidate materials
and elsewhere using a technique called spin-polarized neutron reflectometry. They say the new finding could be used to probe a variety of exotic physical phenomena,
Possible applications of the new findings include the creation of spintronics, transistors based on the spin of particles rather than their charge.
This includes the study of predicted physical phenomena such as Majorana fermions, particles predicted in 1937 but not yet observed, which,
unlike all known subatomic particles, serve as their own antiparticles. These theorized particles ave yet to be explored.
It opens another avenue to explore these things he says. he significance of this work is threefold,
says Qi-Kun Xue, a professor of physics at Tsinghua University in China who was involved not in this work.
#Information storage and retrieval in a single levitating colloidal particle Thanks to this new technique developed by scientists at the University of Zurich,
'click on image to enlarge) Colloids are minute particles that are distributed finely throughout a liquid.
Suspensions of colloidal particles are most familiar to us as beverages, cosmetics and paints. At a diameter in the range of ten to one hundred nanometres, a single such particle is invisible to the naked eye.
These nanoparticles are constantly in motion due to the principle of Brownian motion. Since the particles are charged electrically,
they experience forces of attraction and repulsion that can be harnessed to control and manipulate their behavior.
They were able to organise the tiny particles into new structures with the utmost precision
and each individual particle can now be used to store and retrieve data, "explains Madhavi Krishnan.
#Electrons that stick together, superconduct together The discovery of a surprising feature of superconductivity in an unconventional superconductor by a RIKEN-led research team provides clues about the superconducting mechanism in this material
Superconductivity occurs as the result of pairs of electrons binding together in such a way that they act as a single quasiparticle.
the binding force is provided by vibrations in the atomic lattice through which the electrons travel.
or spin fluctuation of the electrons themselves, which binds electrons in pairs through the entanglement of electron spins.
However recent experiments have shown that this mechanism cannot explain the superconducting state in the quintessential unconventional superconductor Cecu2si2.
Inspired by this result, Michi-To Suzuki and Ryotaro Arita from the RIKEN Center for Emergent Matter Science, in collaboration with Hiroaki Ikeda from Ritsumeikan University in Japan, investigated the mechanism of electron pairing in 2si2
The electrons in Cecu2si2 can interact by entanglement of both spin and orbital states, resulting in multiple possible configurations or degrees of freedom.
but to their surprise, the researchers found that multipole fluctuations can also produce bound pairs of electrons,
This kind of electron binding may also be present in the recently discovered class of high-temperature iron-based superconductors. e found that the origin of the unconventional superconductivity in Cecu2si2 is an exotic multipole degree of freedom consisting of entangled spins
and have applications in superresolution microscopy, laser cutting, and particle acceleration.""You generally would need a large optical setup,
#Quantum dot solar cell exhibits 30-fold concentration We've achieved a luminescent concentration ratio greater than 30 with an optical efficiency of 82-percent for blue photons,
and photonic mirrors suffer far less parasitic loss of photons than LSCS using molecular dyes as lumophores.
and reabsorption and scattering of propagating photons. We replaced the molecular dyes in previous LSC systems with core/shell nanoparticles composed of cadmium selenide (Cdse) cores
while reducing photon re-absorption, says Bronstein. The Cdse/Cds nanoparticles enabled us to decouple absorption from emission energy and volume,
and excel at transmitting electrons and heat. But when the two are joined, the way the atoms are arranged can influence all those properties. ome labs are actively trying to make these materials or measure properties like the strength of single nanotubes and graphene sheets,
#Physicists discover spiral vortex patterns from electron waves In their new study("Electron Vortices in Photoionization by Circularly Polarized Attosecond Pulses),
when an electron is ejected, or ionized, from its orbit around a helium atom. Like all subatomic particles, electrons occupy a realm governed by quantum mechanics.
This means that their position, velocity and other properties are probabilistic, existing within a range of possible values.
Electrons can also exhibit the behavior of waves that, like ripples in a pond often gain or lose amplitude as they cross paths.
By firing two time-delayed, ultrashort laser pulses at a helium atom, the researchers found that the distribution of momentum values for these intersecting electron waves can take the form of a two-armed vortex that resembles a spiral galaxy.
the team study is the first to produce the pattern with electrons. In doing so, it also dramatically demonstrates the wavelike property of matter,
Starace called the pattern an xcellent diagnostic toolfor characterizing electron-manipulating laser pulses which occur on such fast time scales that physicists have sought multiple ways to measure their durations and intensities.
whereas the duration of the pulses corresponds to the width of the arms. f you use (longer) pulses to probe the electrons,
in materials revealed by electron tomography")."For more than 100 years, researchers have inferred how atoms are arranged in three-dimensional space using a technique called X-ray crystallography,
which a beam of electrons smaller than the size of a hydrogen atom is scanned over a sample
and measures how many electrons interact with the atoms at each scan position. The method reveals the atomic structure of materials
because different arrangements of atoms cause electrons to interact in different ways. However scanning transmission electron microscopes only produce two-dimensional images.
The downside of this technique is repeated that the electron beam radiation can progressively damage the sample.
thanks to the electron beam energy being kept below the radiation damage threshold of tungsten. Miao and his team showed that the atoms in the tip of the tungsten sample were arranged in nine layers, the sixth
and some of those photons interfere with one another and find their way onto a detector,
a computer then reconstructs the path those photons must have taken, which generates an image of the target material--all without the lens that's required in conventional microscopy."
The table-top machines are unable to produce as many photons as the big expensive ones
hardly any photons will bounce off the target at large enough angles to reach the detector.
Without enough photons, the image quality is reduced. Zürch and a team of researchers from Jena University used a special, custom-built ultrafast laser that fires extreme ultraviolet photons a hundred times faster than conventional table-top machines.
With more photons, at a wavelength of 33 nanometers, the researchers were able to make an image with a resolution of 26 nanometers--almost the theoretical limit."
"Nobody has achieved such a high resolution with respect to the wavelength in the extreme ultraviolet before, "Zürch said.
noninvasive 3d biomedical imaging photonic chips aerospace photonics micromachines laser tweezing the process of using lasers to trap tiny particles.
nanometer particles with the ability to absorb light and re-emit it with well-defined colors.
where the particle size determines the color of the emitted light. The new strategy relies on a completely different physical mechanism;
Further, the exceptional clarity of the transparent silk gels enabled the laser's photons to be absorbed nearly 1 cm below the surface of the gel-more than 10 times deeper than with other materials
whereby atomic nuclei melt together and release energy. Because of the low binding energy of the tiny atomic nuclei, energy can be released by combining two small nuclei with a heavier one.
A collaboration between researchers at the University of Gothenburg and the University of Iceland has been to study a new type of nuclear fusion process.
This produces almost no neutrons but instead fast, heavy electrons (muons), since it is based on nuclear reactions in ultra-dense heavy hydrogen (deuterium)."
since the neutrons produced by such processes can cause dangerous flash burns, "says Leif Holmlid, Professor Emeritus at the University of Gothenburg.
"A considerable advantage of the fast heavy electrons produced by the new process is that these are charged
The energy in the neutrons which accumulate in large quantities in other types of nuclear fusion is difficult to handle
because the neutrons are charged not. These neutrons are high-energy and very damaging to living organisms,
whereas the fast, heavy electrons are considerably less dangerous.""Neutrons are difficult to slow down or stop and require reactor enclosures that are several metres thick.
Muons-fast, heavy electrons-decay very quickly into ordinary electrons and similar particles. Research shows that far smaller and simpler fusion reactors can be built.
The next step is to create a generator that produces instant electrical energy y
#A new single-molecule tool to observe enzymes at work A team of scientists at the University of Washington
and the biotechnology company Illumina have created an innovative tool to directly detect the delicate, single-molecule interactions between DNA and enzymatic proteins.
The nanoparticle hydrophilic layer essentially locks in the active ingredient, a hydrophobic chemical called padimate O. Some sunscreen solutions that use larger particles of inorganic compounds, such as titanium dioxide or zinc oxide,
"In this work, we have made two major advances--the ability to precisely control the brightness of light-emitting particles called quantum dots,
and tunable number of photons per tagged biomolecule. They are expected also to be used for precise color matching in light-emitting devices and displays,
and for photon-on-demand encryption applications. The same principles should be applicable across a wide range of semiconducting materials."
The scientists developed a nanoscale photodetector that uses the common material molybdenum disulfide to detect optical plasmons--travelling oscillations of electrons below the diffraction limit
rather than solely to the laser's wavelength, demonstrating that the plasmons effectively nudged the electrons in Mos2 into a different energy state."
and deposited metal contacts onto that same end with electron beam lithography. They then connected the device to equipment to control its bias,
the energy was converted into plasmons, a form of electromagnetic wave that travels through oscillations in electron density.
This energy electronically excited an electron once it reached the molybdenum disulfide-covered end effectively generating a current.
Düsseldorf, Mainz, Princeton and Santa barbara, a ring of colloidal particles are localised in optical tweezers and automatically translated on a circular path,
Through optical manipulation the particle ring can be squeezed at will, altering the coupling between the driven and loaded parts of the assembly and providing a clutch-like operation mode."
which harness the science of the very small-the strange behaviour of subatomic particles-to solve computing challenges that are beyond the reach of even today's fastest supercomputers.
"We've morphed those silicon transistors into quantum bits by ensuring that each has only one electron associated with it.
We then store the binary code of 0 or 1 on the'spin'of the electron,
which is associated with the electron's tiny magnetic field, "he added. Dzurak noted that that the team had patented recently a design for a full-scale quantum computer chip that would allow for millions of our qubits,
#Physicists turn toward heat to study electron spin The quest to control and understand the intrinsic spin of electrons to advance nanoscale electronics is hampered by how hard it is to measure tiny, fast magnetic devices.
Applied physicists at Cornell offer a solution: using heat, instead of light, to measure magnetic systems at short length and time scales.
"Why the interest in electron spin? In physics, electron spin is established the well phenomenon of electrons behaving like a quantum version of a spinning top,
and the angular momentum of these little tops pointing por own. An emerging field called spintronics explores the idea of using electron spin to control
and store information using very low power. echnologies like nonvolatile magnetic memory could result with the broad understanding and application of electron spin.
Spintronics, the subject of the 2007 Nobel prize in Physics, is already impacting traditional electronics, which is based on the control of electron charge rather than spin. irect imaging is really hard to do,
Fuchs said. evices are tiny, and moving really fast, at gigahertz frequencies. Wee talking about nanometers and picoseconds.
When the electrons are travelling through a magnetic whirl, they feel the canting between the atomic magnets,
or high-energy reservoir of electrons. Lithium can do that, as the charge carrier whose ions migrate into the graphite
DNP-enhanced sensitivity Traditional NMR uses the magnetic properties of atomic nuclei to reveal the structures of the molecules containing those nuclei.
because it only allows you to obtain information from the carbon-13 nuclei in a sample,
which requires transferring polarization from unpaired electrons to protons and then carbon nuclei, using microwaves generated by a gyrotron,
and electrons to read data Scientists from Kiel University and the Ruhr Universität Bochum (RUB) have developed a new way to store information that uses ions to save data
and electrons to read data. This could enable the size of storage cells to be reduced to atomic dimensions.
Standard memory devices are based on electrons which are displaced by applying voltage. The development of ever smaller and more energy-efficient storage devices according to this principle,
"Electrons are roughly 1000 times lighter than ions and so they move much more easily under the influence of an external voltage.
while the electrons remain mobile and can be used to read the storage status."The trick:
"The tunnel effect enables us to move electrons through the ultra-thin layer with very little energy,
and electrons, on the other hand, at voltages far below one volt. This way, ions can be used specifically for storing and electrons specifically for reading data.
The researchers also reported that their research had another very interesting element. The new resistance-based storage devices could even simulate brain structures.
which involves the gaining of electrons. The reduced-graphene oxide-coated materials were found to be particularly sensitive to detecting nitrogen dioxide
Ultrafast electron pulses are one tool scientists use to probe the atomic world. When the pulses hit the atoms in a material, the electrons scatter like a wave.
By setting up a detector and analyzing the wave interference pattern, scientists can determine information like the distance between atoms.
Conventional electron pulse technology uses a static magnetic field to compress the electrons transversely. However, the static field can interfere with the electron source and the sample and lead to temporal distortion of the electron pulses--both
of which can lead to lower quality images. To avoid the problems associated with static field compression the MIT
and SIMTECH team proposed the first all-optical scheme for compressing electron pulses in three dimensions
In the scheme, laser pulses, functioning as three-dimensional lenses in both time and space, can compress electron pulses to attosecond durations and sub-micrometer dimensions,
providing a new way to generate ultrashort electron pulses for ultrafast imaging of attosecond phenomena."
one can compress electron pulses by as much as two to three orders of magnitude in any dimension or dimensions with experimentally achievable laser pulses.
This translates, for instance, to reducing the duration of an electron pulse from hundreds of femtoseconds to sub-femtosecond scales,
Compressing Electron Pulses In time and Space Short pulse durations are critical for high temporal resolution in ultrafast electron imaging techniques.
To ensure that the electron pulse arrives at the sample or detector with the desired properties in spite of inter-electron repulsion
ultrafast electron imaging setups usually require means to compress the electron pulse both transversely and longitudinally.
which are coils of wire that create uniform magnetic fields, to focus the electron beams. The use of static field elements can lead to the undesirable presence of static magnetic fields on the electron source (cathode)
and the sample and can also cause temporal distortions when transporting ultrashort electron pulses. To solve these problems,
Wong's team conceived an all-optical scheme that focuses electron pulses in three dimensions by using a special type of laser mode with an intensity"valley"(or minimum) in its transverse profile,
which is technically known as a"Hermite-Gaussian optical mode.""The pulsed laser modes successively strike the moving electrons at a slanting angle, fashioning a three-dimensional trap for the electrons."
"To compress the electron pulse along its direction of travel, for instance, the laser-electron interaction accelerates the back electrons
and decelerates the front electrons. As the electrons propagate, the back electrons catch up with the front electrons, leading to temporal compression of the electron pulse,
"Wong explained. The force that the optical field exerts on the electrons is called the optical ponderomotive force,
a time-averaged force that pushes charged particles in a time-varying field towards regions of lower intensity."
"Just as conventional lenses can be used to focus a light beam, our configuration can be used to focus an electron beam.
In our case, however, we can perform the focusing not only in the dimensions perpendicular to the direction of travel,
but also in the dimension parallel to the direction of travel. Hence, the entire setup can be seen as a spatiotemporal lens for electrons,
"Wong said. By modeling the fields with exact solutions of Maxwell equations and solving the Newton-Lorentz equation,
which together describe classical optical and electromagnetic behavior, Wong and his collaborators have analytically and numerically demonstrated the viability of their scheme.
Among their findings is the fact that the longitudinal compression is sensitive to the laser pulse incidence angle,
which is a function of the electron pulse velocity for optimal performance. A major cost-saving feature in the proposed scheme is the fact that a single optical pulse can be used to implement a succession of compression stages.
Since the scheme allows laser pulses to be recycled for further compression of the same electron pulse (not restricted to the same dimension),
Besides being of great interest in ultrafast electron imaging for compressing both single-and multi-electron pulses
the proposed scheme is potentially useful for focusing other particles such as accelerated protons and neutral atoms.
Broader applications include the creation of flat electron beams and the creation of ultrashort electron bunches for coherent terahertz emission in free-electron based terahertz generation schemes,
"Graphene, a one-atom-thick, two-dimensional sheet of carbon atoms, is known for moving electrons at lightning speed across its surface without interference.
and stop electrons at will via band-gaps, as they do in computer chips. As a semimetal, graphene naturally has no band-gaps,
a technique using electrons (instead of light or the eyes) to see the characteristics of a sample,
Data gathered from the electron signatures allowed the researchers to create images of the material's dimensions and orientation.
and extent to which electrons scattered throughout the material.""We're looking at fundamental physical properties to verify that it is, in fact,
and have developed the world's most efficient quantum bits in silicon using either the electron or nuclear spins of single phosphorus atoms.
A series of electron micrographs showing the barrel-shaped helicase with several components of the replisome:
The electron micrographs show that the replisome is a 20-nanometer sized nanomachine. click on image to enlarge) To test these assumptions,
He studied samples of replisomes from baker's yeast cellsa model for all nucleus-containing cellsprepared and provided by Roxana Georgescu in Michael O'Donnell's research group at Rockefeller University.
right, revealed by electron micrograph images in the current study. Prior to this study scientists believed the two polymerases (green) were located at the bottom
and ability to transport electrons at high speed, but it is also a highly sensitive gas sensor.
Because pore opening disrupts the flow of electrons and protons across the mitochondrial membranes which normally sustains energy production,
-or neutron scattering-based techniques to study them. A different approach The de Pablo group took a completely different approach.
or neutron scattering would be very useful.?Carla Reiter a
#Artificial intelligence System Solves SAT Geometry As well as 11th Graders The Allen Institute for Artificial intelligence (AI2) and University of Washington researchers have created an artificial intelligence (AI) system that can solve SAT geometry questions as well as the average American 11th-grade student, a breakthrough in AI research.
Nothing about the particles told the researchers what the voltages should be, however. They started with random combinations of voltages and learned
The clump of particles has to be cooled to just 0. 3°C above absolute zero, but making the particles smaller would allow the working temperature to rise.
Van der Wiel says there is no reason the approach couldn work at room temperature. Van der Wiel hopes the research will lead to specialised processors that can solve problems such as pattern recognition
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