Tag Archives: electrons

Electrons in Graphene Accelerate to Supersonic Speeds

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Hydraulic jumps occur when swift and slow streams of water intersect at a boundary.

Durk Gardenier / Alamy

Researchers have achieved an unprecedented feat: accelerating electrons to supersonic speeds, generating shock waves.

The flow of electricity through devices resembles the flow of a river, yet they differ greatly. Electrons collide with atoms as they traverse matter, while water droplets in a river frequently collide with one another. In 2016, scientists managed to make electrons flow like a viscous liquid in the ultrathin carbon material, graphene. Recently, Cory Dean and his team at Columbia University in New York have taken this further, introducing electrons into graphene, which resulted in a hydraulic jump due to the high speed of particle flow.

Picture a jump in water pressure while doing the dishes. When you turn on a faucet, you experience a similar phenomenon, with a chaotic ring-like border forming in the sink beneath, separating fast and slow flows. “In a way, it’s akin to a sonic boom happening in your kitchen sink,” remarks Doug Natelson from Rice University, who was not involved in the study.

Designing the electronic version was a complex task. The researchers crafted a microscopic nozzle using two layers of graphene, emulating the “de Laval nozzle,” a design from the 19th century often utilized in rocket engines. This nozzle is tapered in the center, allowing fluid to maintain acceleration and produce a shock wave upon exit if it reaches supersonic speeds within the constriction.

However, detecting the hydraulic jump posed a challenge, as it had never been observed with electrons before. Team member Abhay Pasupathy explains that instead of measuring electrons’ flow as usual, they utilized a specialized microscope to map the voltage at various points along the nozzle.

Natelson notes the intricate process of refining the graphene structure to ensure the electrons could “puff it in the cheek,” meaning they had to compress it sufficiently to enter this more dramatic phenomenon. The team’s achievement in resolving the hydraulic jump is technically remarkable, given the minuscule size of the graphene nozzle, according to Thomas Schmidt at the University of Luxembourg.

Now that they can accelerate electrons to such speeds, researchers aim to explore long-standing inquiries concerning charged shock waves. Dean mentions an ongoing debate about whether hydraulic jumps emit radiation that could potentially be harnessed for new infrared or radio generators. “Every experimenter we’re discussing with is figuring out how to detect this emission. Conversely, there’s a prevailing opinion among theorists that no emissions occur. There remains uncertainty about what is truly happening,” he concludes.

Topics:

  • Electricity/
  • Fluid Mechanics

Source: www.newscientist.com

The Interaction of Fast-Moving Electrons and Photons Drives X-Ray Emission in Blazar Jets

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A recent study utilized NASA’s IXPE (Imaging X-ray Polarized Explorer) to analyze a highly relativistic jet originating from the Blazar Bl Lacertae, a supermassive black hole surrounded by luminous discs.

This artist’s rendering illustrates the core area of Blazar Bl Lacertae, featuring an ultra-massive black hole surrounded by bright discs and Earth-directed jets. Image credit: NASA/Pablo Garcia.

Astrophysicists elucidated a highly relativistic jet, proposing two competing theories regarding an X-ray component made up of protons and electrons.

Each theory presents a distinct signature in the polarization characteristics of the X-ray light.

Polarized light signifies the average direction of the electromagnetic waves comprising light.

When X-rays in a black hole’s jets are highly polarized, it indicates production from protons that circulate within the magnetic field of the jet or protons interacting with the jet’s photons.

Conversely, low polarization in X-rays implies that the generation of X-rays occurs through electron-photon interactions.

The IXPE is the sole satellite capable of making such polarization measurements.

“This was one of the greatest mysteries involving supermassive black hole jets,” remarks Dr. Ivan Agdo, an astronomer at Astrophicidae Athtrophicidae and Andocia-CSIC.

“Thanks to numerous supporting ground telescopes, IXPE equipped us with the necessary tools to ultimately resolve this issue.”

Astronomers concluded that electrons are likely the source, through a process known as Compton scattering.

This phenomenon, also referred to as the Compton effect, occurs when photons lose or gain energy through interactions with charged particles (primarily electrons).

Within the jets of a supermassive black hole, electrons move at speeds approaching that of light.

IXPE enabled researchers to determine that, in Blazar jets, electrons possess enough energy to scatter infrared photons into the X-ray spectrum.

Bl Lacertae, one of the earliest discovered Blazars, was initially thought to be a kind of star in the Lacerta constellation.

IXPE monitored Bl Lacertae for seven days in November 2023, in conjunction with several ground-based telescopes also measuring optical and radio polarization.

Interestingly, during the X-ray polarization observations, Bl Lacertae’s light polarization peaked at 47.5%.

“This marks not only the most polarized BL Lacertae has been in the past 30 years, but indeed the highest ever recorded,” states Dr. Ioannis Riodakis, an astrophysicist at the Institute of Astrophysics.

Researchers noted that X-rays are significantly less polarized than optical light.

They were unable to detect strong polarized signals and ascertained that the X-rays could not exceed 7.6% polarization.

This finding confirms that electron interactions with photons via the Compton effect must account for the X-ray emissions.

“The fact that optical polarization is considerably higher than that of X-rays can only be explained by Compton scattering,” he added.

“IXPE has solved yet another mystery surrounding black holes,” claimed Dr. Enrico Costa, an astrophysicist associated with the planet spaziali of astituto to astituto to n diastrofísica.

“IXPE’s polarized X-ray capabilities have unraveled several long-standing mysteries, which is a significant achievement.

“In other instances, IXPE’s results challenged previously held beliefs, opening up new questions, but that’s the essence of science, and certainly IXPE excels in its scientific contributions.”

Survey results will be published in Astrophysics Journal Letter.

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Ivan Agd et al. 2025. The height of X-ray and X-ray polarization reveals Compton scattering of BL Lacertae jets. apjl in press; doi: 10.3847/2041-8213/ADC572

Source: www.sci.news

Using lasers to transform electrons into mass and charge coils.

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A special laser (red) can bend electrons (blue) into a spiral shape

Dr. Yiqi Fan (University of Konstanz)

With the help of a laser, the electrons were transformed into spiral waves of mass and charge.

“Chirality, or handedness, is an intriguing and still partially mysterious feature of our universe.” Peter Baum Researchers at the University of Konstanz in Germany have discovered that chiral objects, like coils or L-shaped blocks, can be either left- or right-handed, but non-chiral objects, like circles or lines, cannot. Many molecules and materials are inherently chiral, and their function changes depending on whether they are right- or left-handed. But Baum and his colleagues have devised a way to impart chirality to something very small and fundamental: a single electron.

Because electrons are quantum objects, they exhibit both particle-like and wave-like behavior, depending on the experiment. In this experiment, the researchers exploited the wave nature of electrons. First, they create a very fast pulse of electrons and pass it through a thin ceramic membrane. There, the particles encounter a special laser beam. The beam is shaped like a light vortex and, as a result, carries a similarly shaped electromagnetic field. This electromagnetic field affects the wave function, or wave properties, of each electron that passes through it.

Finally, the researchers detected these manipulated electrons and calculated the “expectation values” of each of their masses and charges — that is, the places in space where both properties are most likely to be measured in non-zero quantities. These regions of space formed the shape of a three-dimensional coil, with clearly marked left- or right-handed winding.

Ben McMorran The University of Oregon researchers have previously experimented with making coils of chiral electrons, and they say their new work “represents a very advanced advancement in the state of the art of shaping electrons.” They have demonstrated precise control over the spiraling electrons, which they say will be crucial for using the particles in applications such as imaging and controlling existing materials.

Baum and his colleagues have already found that shining a left-handed coil of electrons at right-handed gold nanostructures results in different ricochet patterns than shining it on left-handed structures, opening up the possibility of using such coils to selectively affect chiral moieties in chemical compounds or electronic devices.

Having created these strange electrons in the lab, Baum says he's now interested in whether they could arise independently in nature: “We're starting to explore these possibilities.”

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Source: www.newscientist.com

Physicists witness real-time movement of electrons in liquid water for the first time

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A research team led by physicists at Argonne National Laboratory isolated the energetic motion of electrons while “freezing” the motion of the much larger atoms they orbit in a sample of liquid water.

Shuai other. Synchronized attosecond X-ray pulse pairs (pictured here in pink and green) from an X-ray free electron laser were used to study the energetic response of electrons (gold) in liquid water on the attosecond time scale. On the other hand, hydrogen (white) and oxygen (red) atoms are “frozen” over time. Image credit: Nathan Johnson, Pacific Northwest National Laboratory.

“The radiation-induced chemical reactions we want to study are the result of targeted electronic reactions that occur on the attosecond time scale,” said lead author of the study, Professor Linda Young, a researcher at Argonne National Laboratory. said.

Professor Young and colleagues combined experiment and theory to reveal the effects of ionizing radiation from an X-ray source when it hits material in real time.

Addressing the timescales over which actions occur will provide a deeper understanding of the complex radiation-induced chemistry.

In fact, researchers originally came together to develop the tools needed to understand the effects of long-term exposure to ionizing radiation on chemicals found in nuclear waste.

“Attosecond time-resolved experiments are one of the major R&D developments in linac coherent light sources,” said study co-author Dr. Ago Marinelli, a researcher at the SLAC National Accelerator Laboratory.

“It's exciting to see these developments applied to new types of experiments and moving attosecond science in new directions.”

Scientists have developed a technique called X-ray attosecond transient absorption spectroscopy in liquids that allows them to “watch” electrons energized by X-rays move into an excited state before larger nuclei move on. “We were able to.

“In principle, we have tools that allow us to track the movement of electrons and watch newly ionized molecules form in real time,” Professor Young said.

The discovery resolves a long-standing scientific debate about whether the X-ray signals observed in previous experiments are the result of different structural shapes or motifs in the mechanics of water or hydrogen atoms.

These experiments conclusively demonstrate that these signals are not evidence of two structural motifs in the surrounding liquid water.

“Essentially, what people were seeing in previous experiments was a blur caused by the movement of hydrogen atoms,” Professor Young explained.

“By recording everything before the atoms moved, we were able to eliminate that movement.”

To make this discovery, the authors used a technique developed at SLAC to spray an ultrathin sheet of pure water across the pulse path of an X-ray pump.

“We needed a clean, flat, thin sheet of water that could focus the X-rays,” said study co-author Dr. Emily Nienhaus, a chemist at Pacific Northwest National Laboratory.

Once the X-ray data was collected, the researchers applied their knowledge of interpreting X-ray signals to recreate the signals observed at SLAC.

They modeled the response of liquid water to attosecond X-rays and verified that the observed signal was indeed confined to the attosecond timescale.

“Using the Hyak supercomputer, we developed cutting-edge computational chemistry techniques that enable detailed characterization of transient high-energy quantum states in water,” study co-authors from the University of Washington said Xiaosong Li, a researcher at Pacific Northwest National University. Laboratory.

“This methodological breakthrough represents a pivotal advance in our quantum-level understanding of ultrafast chemical transformations, with extraordinary precision and atomic-level detail.”

The team worked together to peer into the real-time movement of electrons in liquid water.

“The methodology we have developed enables the study of the origin and evolution of reactive species produced by radiation-induced processes encountered in space travel, cancer treatment, nuclear reactors, legacy waste, etc.,” Professor Young said. Stated.

The team's results were published in a magazine science.

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L. Shuai other. 2024. Attosecond Pump Attosecond Probe X-ray Spectroscopy of Liquid Water. science, published online on February 15, 2024. doi: 10.1126/science.adn6059

Source: www.sci.news