Increasing Photon Upconversion Efficiency With Structural Exciton Localization

June 25, 2026 by Maya Posch 13 Comments

In structures like photovoltaic cells there is only a limited spectrum of wavelengths that can perform useful work, with the remaining wavelengths of electromagnetic radiation effectively wasted. If the energy of such wavelengths could be coaxed into this useful spectrum, this could then correspondingly boost the performance of the devices, but doing so is not straightforward. Going from lower-energy photons to higher-energy photons is very inefficient, with a recent study by [Thilini Ishwara] et al. demonstrating a liquid triplet medium that has a conversion efficiency of about 8.2%.

Generally the absorption and emission of electromagnetic radiation involves a shift to a lower energy state, the Stokes shift, but the inverse anti-Stokes shift – the goal of photon upconversion – is decidedly less common, even if it finds uses today in for example industrial pigments that can absorb in the near-infrared and re-emit in the visible spectrum. This is practical in luminescent displays and anti-counterfeiting measures, where details like conversion efficiency aren’t paramount.

Unlike the Stokes shift, the mechanisms that underlie the anti-Stokes shift either require cooperation from the material’s lattice, or – in the case of organic molecules – what is termed triplet-triplet annihilation (TTA), also known as photochemical upconversion (PUC). This involves an absorbing species, a sensitizer and an emitting species, allowing for the summing of multiple lower-energy photons into a higher-energy photon, with this 2023 review article by [Jiale Feng] et al. providing a good primer.

In the study by [Ishwara] et al. this triplet medium is 9,10-bis(n-octyl-diisopropylsilylethynyl)anthracene (NODIPS-An), affixed to a nanostructured alumina scaffold (see top image). After characterizing the assembled device and taking internal losses due to e.g. reabsorption into account, the final conversion efficiency of 8.2% was established.

Of course, TTA isn’t the only way to do PUC, with SOMET (singlet oxygen mediated energy transfer) being an alternative approach, with [Roslyn Forecast] et al. comparing the two in a 2023 article. As noted in its conclusion SOMET is currently most suited to PUC to the red and infrared regions of the spectrum. For now research continues with no clear path to commercialization visible yet.

Bortle-1 Skies in the heart of darkest Texas.

“Telescope Rancher” Is The Coolest Job You Didn’t Know Existed

June 22, 2026 by Tyler August 36 Comments

McCulloch County, Texas, is smack dab in the middle of a very large state. We wouldn’t exactly call it the middle of nowhere, but given there’s so little light pollution it scores a 1 on the Bortle Scale, it’s not exactly the Big Apple, either. [Bray Falls] lives there, and has a job description we have become immediately jealous of: [Bray] is a telescope rancher.

Like the song goes, the stars really are big and bright at night deep in the heart of Texas. Not only is his ranch free of the light pollution that plagues more urban locations, central Texas is pretty dry, with only a few days of rain in any given month. That’s not great for agriculture, but it’s great for astronomy since it means the skies are most often cloud-free. Combine that with access to high-speed internet, and you have the makings of a telescope ranch.

Telescopes being let out of the barns for the night.
Image: Starfront Observatory

It’s brilliant in its simplicity: along with his own ‘scopes, [Bray]’s Starscope Observatory hosts hundreds of other people’s CCD equipped goto telescopes, all set up to be remote controlled over the information superhighway. On clear nights– which again, is most of them–the roofs roll off the telescope barns and observations can begin. Pad rental comes with tech support, too, so you don’t have to fly out to heart of darkest Texas if your mount gets jammed or you lose signal for any reason. That said, you should be sure to read the fine print before signing up, because said tech support probably doesn’t apply if you 3D printed your own ‘scope, or built your own mount.

That said, having gone to the effort of doing all that, would you really send your baby away to a farm upstate? Best reserve that for the old Celestron collecting dust in the corner. If you think we should be leaving these observations to the pros, be aware [Bray] has apparently discovered a very oddly-placed supernova remnant, 40 degrees off the galactic plane in Virgo. So this isn’t just a rewarding hobby; it’s still science, too.

Figure showing the simulated path of gas released in GEO to the magentosheath.

An Orbital StormWall Could Mitigate The Next Carrington Event

June 17, 2026 by Tyler August 40 Comments

The Carrington Event was the most intense geomagnetic storm ever recorded. In September 1859, auroras were visible as close to the equator as Columbia and some telegraph stations were severely damaged by current induced in the lines. If a similar event occurred today, with a lot more more wiring to pick up current than just an embryonic telegraph network, the results would almost certainly be cataclysmic.

Various modifications to the grid have been proposed to avoid another storm of that magnitude bringing on a new dark age, but a recent paper in the journal Space Weather proposes a more radical solution: using the sun’s energy to create a massive barricade in space.

Time evolution of a simulated geomagnetic storm, with and without the StormWall.

While the authors of the paper refer to this concept by the compelling name StormWall, it’s not a physical wall. It’s actually just gas, likely of alkali metal atoms, to be deployed by solar-powered satellites.

To oversimplify, the proposal is to release lots and lots of neutral gas in Geosynchronous Earth Orbit (GEO), in what the researchers call “artificial mass loading” — the neutral gas would of course be ionized by the storm, but in so doing could absorb up to 50% of the incoming energy of the geomagnetic storm, frustrating its coupling to Earth’s magnetosphere. As a bonus, it would protect not just terrestrial assets like the power grid, but everything in a lower orbit than the mass load: everything from communication satellites in GEO to the International Space Station. Assuming its hasn’t been reduced to debris laying at the bottom of Point Nemo by then, anyway.

In simulations, the StormWall required 384,048 kg of gas, which is not exactly trivial. But even accounting for tanking, the researchers estimate that would only take about six launches of SpaceX’s Starship. Though that does assume its GEO capabilities end up being roughly equivalent to the massive vehicle’s projected 100-tons-to-Mars payload capacity.

It’s certainly an interesting hack to solve a problem that has caused a lot of worry these past decades. If you’re interested in learning more about the record-setting geomagnetic storm, we have a piece about the 1859 Carrington Event that should give you plenty of anxiety about the frailty of our modern infrastructure.

A selection of materials sits on a counter. There is a fluorescent light bulb, two papers stained with dyes, and a few other pieces of paper with no obvious staining.

Building Your Own X-Ray Detector Screen

June 14, 2026 by Aaron Beckendorf 8 Comments

Fluoroscopy is probably the best-known method of X-ray imaging: an X-ray beam passes through the subject to be imaged, and the transmitted X-rays illuminate a phosphor screen. Dense objects, such as metal or bone, cast a shadow on the screen, which provides a real-time image of the subject’s interior. Already having access to X-ray sources, [MarcellF]’s next step was to investigate common phosphor materials, then synthesize his own.

Most common materials that fluoresce under ultraviolet light showed no activity under X-rays: fluorescein, quinine, UV fluorescent paint, and common fluorescent minerals emitted no noticeable glow under 80 kV X-ray stimulation. However, strontium aluminate phosphors did fluoresce well, with a strong afterglow, as did the phosphors in a fluorescent light bulb, some LEDs, and an electroluminescent panel. The electroluminescent panel, which used a zinc sulfide phosphor, was almost as bright as the gadolinium oxysulfide screen from a CT scanner’s detector and had no noticeable afterglow.

Continue reading “Building Your Own X-Ray Detector Screen” →

The Pacemaker Patch

June 13, 2026 by Al Williams 36 Comments

A pacemaker is implanted to send signals that regulate a patient’s heartbeat, and to do that, you need power. That means they require battery changes, and when the device in question happens to be inside your chest, that means surgery. Sometimes as often as every five years. [Alex Music] writing in Spectrum notes that researchers have a new paper discussing a possible alternative: a tiny patch stuck to the outside of the chest that uses ultrasound to pace the heart rhythm.

Rats, pigs, and human heart cell samples have all responded to the system. You might wonder how ultrasound could make your heart beat, but the new pacemaker relies on gene therapy to sensitize your heart cells to the high-frequency waves. The therapy is delivered by a simple injection.

In addition to the chest patch, the patient would need a data and power module that they could keep in their pocket. The gene therapy doesn’t alter your DNA but introduces RNA to make heart cells produce a sound-sensitive protein in the cell’s ion channels. When stimulated, the ion channels admit calcium, which causes the heart to beat.

Pacemakers are nothing less than a modern technological marvel. Maybe if this catches on, cheap junked pacemakers will show up on the surplus market. They could be useful.

Converting A Scanning Electron Microscope Into A TEM Is Surprisingly Easy

June 13, 2026 by Maya Posch 6 Comments

Although both a SEM and a TEM are electron microscopes, their working principles and images are very different. Whereas an SEM uses secondary electrons ejected after bombarding a sample’s surface with primary electrons, a TEM works more like an X-ray machine, with a sensor placed behind the sample to record primary electrons after they pass through said sample. It is, however, possible to turn a SEM into a TEM with some creativity, as [ProjectsInFlight] recently did with his SEM.

We previously covered how the SEM in the video was saved from being scrapped and subsequently revived, and now it is getting a pretty nice upgrade. That said, this SEM to TEM change isn’t anything new, with so-called STEM imaging having been possible for ages using a rather simple reflecting adapter. The problem here is that such adapters cost enough to make you dread filing a budget request, yet they are simple enough that you might be able to DIY one.

The main concern with the DIY adapter was clearance between the sample holder and the fragile components inside the chamber. This turned out to be a hair under 14 mm (0.55″), giving not a lot of space to work with, but that was relative to the standard bulky sample holder. With a thinner sample plate machined out of aluminum, significantly more space became available, including for the primary electron mirror and shield for the secondary electrons.

Some more lathe, milling, and tapping work later, the entire sample holder came together. During testing a hack was implemented to enable adjusting the mirror angle while in the evacuated vacuum chamber so that the adapter could be dialed-in. Subsequently, a first sample was imagined in the form of gold nanoparticles, which revealed a leaky secondary electron shield due to bypassing.

Further testing revealed that the shield needed to extend much higher to meaningfully block secondary electrons, after which the TEM image massively improved. Subsequently, a previously expired mosquito graciously donated its wings to science, with TEM imaging clearly revealing the delicate structures within these wonders of evolutionary design.

The next challenge will be to TEM image biological cells, which require substantial preparation.

This isn’t the first STEM converter we’ve seen. The SEM has a long checkered history that we’ve talked about before, too.

Continue reading “Converting A Scanning Electron Microscope Into A TEM Is Surprisingly Easy” →

Introducing Boron Buckyballs

June 10, 2026 by Maya Posch 17 Comments

A buckminsterfullerene, also known as a buckyball, is typically a fullerene consisting of sixty carbon atoms (C₆₀) arranged in a way that resembles a football-like sphere. Extending this arrangement to other types of atoms has until now however proven as elusive as finding non-carbon-based lifeforms. In a paper by [Hyun Wook Choi] et al. and published in Chemical Science the discovery of boron buckyballs is detailed. There is also a soft-paywalled article in the Chemical & Engineering News magazine for a higher-level perspective.

The discovered boron-based buckyball ups the number of atoms to eighty, forming B₈₀ (boron fullerite) with a slightly larger diameter than C₆₀ at 0.85 nm versus 0.71 nm. Perhaps more interesting are the claims by the authors that boron fullerite may have more practical applications than its carbon-based cousin, mostly due to it being predicted to be a semiconductor with an 0.8 eV energy gap and better electron acceptance that provides interesting doping prospects.

Producing these boron structures used laser vaporization with a helium carrier gas that was seeded with argon to increase cooling efficiency. Inside this boron cluster the reported structures were then discovered and characterized as described in the paper.

Obviously, going from a fascinating laboratory discovery to bulk production won’t be easy, and the predicted properties of boron fullerite may turn out to be incomplete or have a dark side that we aren’t aware of. Regardless, they’re bound to be more useful at least than the carbon version that’s remained mostly a curiosity despite many years of research.