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Category: particle physics – Page 389

Smaller than ever—exploring the unusual properties of quantum-sized materials

The development of functional nanomaterials has been a major landmark in the history of materials science. Nanoparticles with diameters ranging from 5 to 500 nm have unprecedented properties, such as high catalytic activity, compared to their bulk material counterparts. Moreover, as particles become smaller, exotic quantum phenomena become more prominent. This has enabled scientists to produce materials and devices with characteristics that had been only dreamed of, especially in the fields of electronics, catalysis, and optics.

But what if we go smaller? Sub-nanoparticles (SNPs) with particle sizes of around 1 nm are now considered a new class of materials with distinct properties due to the predominance of quantum effects. The untapped potential of SNPs caught the attention of scientists from Tokyo Tech, who are currently undertaking the challenges arising in this mostly unexplored field. In a recent study published in the Journal of the American Chemical Society, a team of scientists from the Laboratory of Chemistry and Life Sciences, led by Dr. Takamasa Tsukamoto, demonstrated a novel molecular screening approach to find promising SNPs.

As one would expect, the synthesis of SNPs is plagued by technical difficulties, even more so for those containing multiple elements. Dr. Tsukamoto explains: “Even SNPs containing just two different elements have barely been investigated because producing a system of subnanometer scale requires fine control of the composition ratio and particle size with atomic precision.” However, this team of scientists had already developed a novel method by which SNPs could be made from different metal salts with extreme control over the total number of atoms and the proportion of each element.

Stronger and Faster Than Lightning: Scientists Achieve Rare Quantum State in Polycrystals

Scientists from the Max Planck Institute for Polymer Research, Paderborn University, and the University of Konstanz have succeeded in achieving a rare quantum state. They are the first to have demonstrated Wannier-Stark localization in a polycrystalline substance. Predicted around 80 years ago, the effect has only recently been proven — in a monocrystal. Until now, researchers assumed this localization to be possible only in such monocrystalline substances which are very complicated to produce. The new findings represent a breakthrough in the field of physics and could in future give rise to new optical modulators, for example, that can be used in information technologies based on light, among other things. The physicists have published their findings in the well-respected technical journal, Nature Communications.

Stronger and faster than lightning

The atoms of a crystal are arranged in a three-dimensional grid, held together by chemical bonds. These bonds can, however, be dissolved by very strong electric fields which displace atoms, even going so far as to introduce so much energy into the crystal that it is destroyed. This is what happens when lightning strikes and materials liquefy, vaporize or combust, for example. To demonstrate Wannier-Stark localization, the scientists’ experiments involved setting up electric fields of several million volts per centimeter, much stronger than the fields involved in lightning strikes. During this process, the electronic system of a solid — in this case, a polycrystal — is forced far from a state of equilibrium for a very short time. Wannier-Stark localization involves virtually shutting down some of the chemical bonds temporarily. This state can only be maintained for less than a picosecond — one millionth of one millionth of a second — without destroying the substance.

Astronomers See an Enormous Shockwave — 60x Bigger Than the Entire Milky Way Galaxy

Astronomers have a thing for big explosions and collisions, and it always seems like they are trying to one-up themselves in finding a bigger, brighter one. There’s a new entrant to that category – an event so big it created a burst of particles over 1 billion years ago that is still visible today and is 60 times bigger than the entire Milky Way.

That shockwave was created by the merger of two galaxy clusters to create a supercluster known as Abell 3667. This was one of the most energetic events in the universe since the Big Bang 0, according to calculations by Professor Francesco de Gasperin and his time from the University of Hamburg and INAF. When it happened over 1 billion years ago, it shot out a wave of electrons, similar to how a particle accelerator would. All these years later, those particles are still traveling at Mach 2.5 (1500 km/s), and when they pass through magnetic fields, they emit radio waves.

Local nuclear reactor helps scientists catch and study neutrinos

A nuclear reactor at an Illinois energy plant is helping University of Chicago scientists learn how to catch and understand the tiny, elusive particles known as neutrinos.

At Constellation’s (formerly Exelon) Dresden Generating Station in Morris, Illinois, the team took the first measurements of coming off a with a tiny detector. These particles are extremely hard to catch because they interact so rarely with matter, but power reactors are one of the few places on Earth with a high concentration of them.

“This was an exciting opportunity to benefit from the enormous neutrino production from a reactor, but also a challenge in the noisy industrial environment right next to a reactor,” said Prof. Juan Collar, a particle physicist who led the research. “This is the closest that neutrino physicists have been able to get to a commercial reactor core. We gained unique experience in operating a detector under these conditions, thanks to Constellation’s generosity in accommodating our experiment.”

PLAN A: Our team developed a simulation for a plausible escalating war between the United States and Russia using realistic nuclear force postures, targets and fatality estimates

It is estimated that there would be more than 90 million people dead and injured within the first few hours of the conflict.

For more, see https://sgs.princeton.edu/the-lab/plan-a.

A collaboration with Alex Wellerstein (http://blog.nuclearsecrecy.com) and Jeff Snyder (https://music.princeton.edu/people/jeff-snyder).

Physics: Speed of Light Could Be Dropped to Zero Using Crystals

In a vacuum like space, the speed of light is just over 186,280 miles per second. Scientists have now shown it’s possible to slow it down to zero miles per second without sacrificing its brightness, regardless of its frequency or bandwidth.

A team of researchers from the Israel Institute of Technology and the Institute of Pure and Applied Mathematics in Brazil discovered a method of theoretically bringing the speed of light to a halt by capitalizing on “exceptional points”—coordinates at which two separate light emissions reach each other and merge into a single one, according to Phys.org. A paper describing the research was published in the scientific journal Physical Review Letters.

The first involves aiming a laser into a cloud of ultracold sodium atoms, the researchers wrote in their paper. When the laser is abruptly switched off, a slow pulse of light is imprinted onto the atoms, essentially bringing the light to a halt by absorbing it; the imprinted shape can then be converted back into a photon. But it’s the second method that allowed the researchers to make their breakthrough.

Catalyst turns carbon dioxide into gasoline 1,000 times more efficiently

Engineers working to reverse the proliferation of greenhouse gases know that in addition to reducing carbon dioxide emissions we will also need to remove carbon dioxide from power plant fumes or from the skies. But, what do we do with all that captured carbon? Matteo Cargnello, a chemical engineer at Stanford University, is working to turn it into other useful chemicals, such as propane, butane or other hydrocarbon fuels that are made up of long chains of carbon and hydrogen.

“We can create gasoline, basically,” said Cargnello, who is an assistant professor of chemical engineering. “To capture as much as possible, you want the longest chain hydrocarbons. Chains with eight to 12 would be the ideal.”

A new catalyst, invented by Cargnello and colleagues, moves toward this goal by increasing the production of long-chain hydrocarbons in chemical reactions. It produced 1,000 times more butane—the longest hydrocarbon it could produce under its maximum pressure—than the standard catalyst given the same amounts of carbon , hydrogen, catalyst, pressure, heat and time. The new catalyst is composed of the element ruthenium—a rare transition metal belonging to the platinum group—coated in a thin layer of plastic. Like any catalyst, this invention speeds up chemical reactions without getting used up in the process. Ruthenium also has the advantage of being less expensive than other high-quality catalysts, like palladium and platinum.