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XXP instrument back online, marking a key milestone in high-energy upgrade to SLAC’s X-ray laser

XPP, the X-ray Pump Probe instrument at the Linac Coherent Light Source (LCLS), is back online and welcoming researchers after a complete rebuild. The overhaul has readied XPP for the significant increase in X-ray output expected from the ongoing high-energy upgrade to LCLS at the Department of Energy’s SLAC National Accelerator Laboratory. LCLS is a pioneering X-ray free-electron laser facility used by scientists around the world to capture ultrafast snapshots of natural processes.

“Completing the XPP rebuild on-time and on-budget is a key milestone for the high-energy upgrade effort, and we’re thrilled that the instrument is back to supporting researchers from around the world,” said John Hogan, project director for the LCLS high-energy upgrade. “This was a huge team effort, involving partners across SLAC’s engineering, science and project teams.”

Since its 2010 debut, XPP has enabled groundbreaking research across materials science—from quantum information storage to material dynamics across timescales—as well as studies in chemistry, physics and bioscience. Researchers have leveraged XPP to pioneer X-ray optics technologies, including cavity-based X-ray oscillators that are shaping future X-ray free-electron laser facilities.

Sudden quantum jolts may not break adiabatic behavior after all

In thermodynamics, an “adiabatic process” is a system change that transfers no heat in or out of the system. Any and all energy change in that system are therefore accomplished by doing work on the system, work being action that moves matter over a distance. (An example is a bicycle tire pump or lifting a box from the floor.)

The “adiabatic theorem” says that if you change a system slowly enough, it will remain in the same energy state. For example, if you walk slowly enough holding a full cup of coffee, the coffee will not spill—the coffee system has time to relax back to its steady state—but if you make a quick and sudden change while holding the coffee cup, some coffee will spill over the cup’s edge.

There is a similar theorem in quantum mechanics—a quantum system that is changed (perturbed) slowly enough will remain in its existing quantum state (often its ground state), while a sudden change, such as a photon impinging upon an atom, changes its energy state.

Twisting water reveals hidden order across four molecular layers at air-water interface

Researchers from the Department of Physical Chemistry at the Fritz Haber Institute and Freie Universität Berlin have revealed the arrangement of water molecules at the interface between liquid water and air. Their findings help to better understand interfacial chemistry, which is largely determined by the specific arrangement of the water molecules. Published in Science Advances, the study shows that one parameter in particular—one that has been neglected until now—is of fundamental importance: the water twist.

Water is arguably the most important molecule on Earth. Interfaces of water play a critical role in numerous processes within physiology, at the ocean surface, and in the atmosphere. In these processes, it is primarily the incredibly thin region of water directly at the boundary that governs their behavior.

Crucially, the sheer presence of the interface perturbs the molecular structure of water, generating preferential orientations and an altered hydrogen-bond network, which give rise to profoundly different properties of water in that region. While these unique structures are at the heart of many interfacial phenomena, characterizing them is monumentally difficult.

A new way to understand the evolution of spacetime dynamics

The concept of spacetime, first described in Einstein’s theory of general relativity, has since been widely studied by many physicists worldwide. Spacetime is described mathematically as a four-dimensional (4D) continuum in which physical events occur, which merges three-dimensional (3D) space, with one-dimensional (1D) time.

This 4D continuum is known to continuously evolve following complex and intricate patterns that are governed by Einstein’s field equations; mathematical equations that describe how matter and energy shape spacetime. While various past theoretical studies explored the evolution of spacetime, identifying patterns that persist during its evolution has proved challenging so far.

Researchers at Adolfo Ibáñez University in Chile and Columbia University set out to explore the evolution of spacetime using ideas rooted in nonlinear electrodynamics, an area of physics that studies the behavior of electric and magnetic fields in complex materials.

Your hand betrays your sense of fairness, and it does so before you even realize it

It turns out that your body is much more truthful about what is and isn’t fair than you might imagine. The rate at which we make physical movements is able to reveal whether our motives are self-interested or retaliatory.

Imagine you’re offered a split of money in an Ultimatum Game: accept a generous share or reject an insultingly low one. Your facial expression might show disgust—but what about your hand?

In new research published in The Royal Society Open Science, scientists report that the speed and vigor of our gestures reveal what we truly care about. In typical choices, people move faster toward bigger rewards; movement vigor usually tracks subjective value. But life’s deals aren’t all about personal gain—notions of fairness and punishment often enter play. Can the way we physically reach for a choice uncover these hidden social motives?

Measurement of nuclear reactions at record-low energies opens new pathways for astrophysics research

An international research team has achieved an important milestone for astrophysics at GSI/FAIR in Darmstadt: In the CRYRING@ESR storage ring, scientists were able to measure nuclear reactions at extremely low energies for the first time, mirroring the conditions inside stars. This novel experimental approach lays the foundation for decoding the formation of elements in the universe with even greater precision in the future.

In the extreme environments of stars, nuclear processes often occur at very low energies. These so-called “sub-MeV energies” (below 1 megaelectron volt) are difficult to replicate in the laboratory because the probability of atomic nuclei interacting at such low speeds is exceptionally small.

In the FAIR storage ring CRYRING@ESR, researchers were able to lower the energy available for the nuclear reaction in the center-of-mass frame of the two particles down to 403 kiloelectron volts. This marks a new record: It is the lowest energy at which a nuclear reaction has ever been measured in a heavy-ion storage ring. The new findings were recently published in the journal European Physical Journal A.

Perovskite solar cells skip yellow phase, degrade more slowly with key additives

Halide perovskites are gaining ground on silicon as a critical material for solar cell technologies: A new study published in the journal Science reports a method to make perovskite-based photovoltaics more durable, allowing the films to attain the desirable black phase of crystal configuration quicker and at lower temperatures while also making it harder to degrade into the inactive yellow phase.

Perovskites are solution-processable materials and can be readily processed as a solution or deposited as vapor. By mixing two key ingredients in the precursor solution, Rice University chemical engineer Aditya Mohite and collaborators have developed perovskite crystalline films that retain 98% of their initial efficiency even after 1,200 hours of exposure under open-circuit voltage conditions to accelerate aging at 90 degrees Celsius (194 degrees Fahrenheit).

The two additives used were a two-dimensional perovskite, which served as a template to guide crystal growth, and formamidinium chloride, a salt molecule that regulates crystallization and has the optimal size to sustain the atomic bonds in the crystal in the right configuration. The two additives create compressive strain in the lattice, driving the formation of the black perovskite phase and stabilizing it, while also steering degradation toward a harder-to-form phase, significantly improving durability.

Light unlocks full polarization control at ultrafast speeds, reshaping photonics

Scientists at Heriot‑Watt University have demonstrated in a world-first, that light can be used to control every aspect of how electromagnetic waves oscillate, opening new technological frontiers. Researchers working in photonics, the science of light, have discovered a new way to control “polarization,” a key property of light that plays a crucial role in the performance of technologies such as drug development and quantum computers.

The breakthrough resolves a long-standing challenge in photonics: achieving control of light that is both fast and strong enough to be useful in real systems. The research, titled All-optical polarization control in time-varying low index films via plasma symmetry breaking, has been published in the journal Nature Photonics.

Dr. Marcello Ferrera, Professor at Heriot-Watt University’s School of Engineering and Physical Sciences, said, How light oscillates has a huge impact on how it interacts with the physical world around us. For the first time, we now have full control over this property of light, for any polarization state, and at ultra‑fast speeds.

Room-temperature multiferroic could pave way to low-energy computing

A team of researchers at Rice University has engineered a new version of a well-known multiferroic that exhibits orders of magnitude higher performance at room temperature than its parent material. The study, published in the Proceedings of the National Academy of Sciences, describes a modified version of bismuth ferrite that shows a 10-fold increase in magnetization and 100-fold increase in magnetoelectric coupling compared to standard varieties.

The synthesis process entailed mixing bismuth ferrite with barium titanate while simultaneously growing the material as a thin film on a substrate that distorts its crystal structure.

“Nobody had ever dialed both knobs—the strain and the chemistry—at once,” said Rice materials scientist Lane Martin, who led the study. “We were able to combine two different material systems into a new material with a new structure and a new combination of properties.”

Superconducting quantum circuit simulates proton tunneling phenomenon in chemical systems

Researchers at Yale, Google, and the University of California-Santa Barbara have created a device that simulates the quantum “tunneling” behavior of protons that occurs in chemistry, a process so common it occurs in everything from photosynthesis to the formation of human DNA.

The advance has the potential to aid researchers across a variety of disciplines, including the development of new solar fuels, pharmaceuticals, and materials. It is described in a new study in the journal PRX Quantum.

Quantum tunneling is a mechanism by which particles, such as electrons or protons, pass through an energy barrier they should not have sufficient energy to cross.

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