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A new, useful absorption limit for ultra-thin films

The applications of ultrathin, conductive films such as those made of graphene have many applications, but it’s been thought their efficacy is limited to absorbing only half of the incidental light at best. A research group in China has now shown that absorption can be as high as 82.8% at light grazing angles nearly parallel to the film. This could not only significantly improve design efficiencies but sheds light on light-matter interactions at sizes much lower than the light’s wavelength. Their work has been published in Physical Review Letters.

Graphene ultrathin films, as thin as one carbon atom (about 0.34 nanometers, 300,000 times thinner than a sheet of paper) have many applications: flexible and transparent electronics, energy storage and batteries, solar cells and photovoltaics, sensors and high-speed electronics and more, where they absorb light.

While such films allow for miniaturizing devices and reducing their weight, their extreme thinness has led to the characterization that they are limited to absorbing only half of the incoming light.

Rydberg atoms detect clear signals from a handheld radio

For the first time, a team of US researchers has used sensors containing highly excited Rydberg atoms to detect signals from an ordinary handheld radio. Through a careful approach to demodulating the incoming signals, Noah Schlossberger and colleagues at the National Institute of Standards and Technology (NIST) were able to recover audio encoded in multiple public radio channels, with promising implications for everyday uses in consumer electronics. The research has been published in Physical Review Applied.

In a Rydberg atom, a single electron is excited to an extremely high energy level, pushing it far from its host atom’s nucleus. From a distance, these atoms resemble a single electron orbiting a positively charged ion.

When any atom is exposed to an external electric field, the positions of its electrons’ energy levels shift through a process called the Stark effect. Yet in a Rydberg atom, the shift becomes far more pronounced, causing particularly striking changes in the spectral patterns produced when the atom is probed by a laser.

Tackling industry’s burdensome bubble problem

In industrial plants around the world, tiny bubbles cause big problems. Bubbles clog filters, disrupt chemical reactions, reduce throughput during biomanufacturing, and can even cause overheating in electronics and nuclear power plants. MIT Professor Kripa Varanasi has long studied methods to reduce bubble disruption.

In a new study, Varanasi, along with Ph.D. candidate Bert Vandereydt and former postdoc Saurabh Nath, have uncovered the physics behind a promising type of debubbling membrane material that is “aerophilic”—Greek for “air-loving.” The material can be used in systems of all types, allowing anyone to optimize their machine’s performance by breaking free from bubble-borne disruptions.

“We have figured out the structure of these bubble-attracting membrane materials to allow gas to evacuate in the fastest possible manner,” says Varanasi, the senior author of the study.

Why you can’t tie knots in four dimensions

We all know we live in three-dimensional space. But what does it mean when people talk about four dimensions? Is it just a bigger kind of space? Is it “space-time,” the popular idea which emerged from Einstein’s theory of relativity?

If you have wondered what four dimensions really look like, you may have come across drawings of a “four-dimensional cube.” But our brains are wired to interpret drawings on flat paper as two-or at most three-dimensional, not four-dimensional.

The almost insurmountable difficulty of visualizing the fourth dimension has inspired mathematicians, physicists, writers and even some artists for centuries. But even if we can’t quite imagine it, we can understand it.

A puddle that jumps: What bubble bursts reveal about water on lotus-like surfaces

Water droplets have a unique ability: They can leap from a surface on their own. This can happen for a variety of reasons, such as when a surface repels water or when heat is involved, such as a water or oil droplet skittering across a hot pan.

It also happens at a very small scale. Up to this point, researchers have observed droplets up to 3 millimeters in diameter exhibiting this behavior. When droplets are larger than that, gravity prevents it from jumping.

A new study published in Nature Physics identifies a previously unreported way to get a puddle of water up to a centimeter wide to jump into the air, something that could support applications from surface cleaning to 3D printing.

How Flawed Crystals Are Powering the Future of Solar Energy

Defect-filled lead-halide perovskites rival silicon solar cells because domain walls inside the material separate and guide charges. Researchers visualized these charge-transport networks using a novel silver-staining technique, resolving a long-standing efficiency mystery. Perovskites made from

Why Does This Galaxy Have Tentacles? Deep Space Mystery Stuns Astronomers

A newly discovered jellyfish galaxy, seen as it existed 8.5 billion years ago, is challenging assumptions about conditions in the early universe. Astrophysicists at the University of Waterloo have identified a newly discovered jellyfish galaxy that is now the most distant example of its kind ever

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