Characterizing Singular Atoms Using X-Ray Spectroscopy And Scanning Tunneling Microscopy

Scanning Tunneling Microscopes (STMs) are amazing tools which can manipulate singular atoms, but they cannot characterize these atoms as they act only on the outer electron shell. Meanwhile X-ray spectroscopy is a great tool for characterizing materials, but has so far been unable to scale down to singular atoms. This is where a recent study (paywalled, see summary article) by Tolulope M. Ajayi and colleagues demonstrates how both STM and X-rays can be combined in order to characterize singular atoms.

Structure of a part of the supramolecular complex used to measure the x-ray absorption spectrum of a single iron atom. The iron atom (red) is held within several ring-shaped structures. (Credit: Ajayi et al., 2023)
Structure of a part of the supramolecular complex used to measure the x-ray absorption spectrum of a single iron atom. The iron atom (red) is held within several ring-shaped structures. (Credit: Ajayi et al., 2023)

This research builds on previous research on synchrotron X-ray STM (SX-STM) which has been used for nanoscale imaging since 2009, but not down to the scale of a singular atom yet. Key to this achievement was to synthesize supramolecular complexes that could act as ‘tweezers’ to hold the atom under investigation in place and away from atoms of the same species. This not only allowed the atom to be identified using SX-STM, it also demonstrated that more subtle chemical properties of the atom can be analyzed in this manner, such as the way it interacts with other atoms.

The information gleaned this way matches up with what we know about the two atoms used in the study: iron and the rare earth terbium, with the latter’s lack of hybridization of its f orbitals (ℓ = 3) observable. For less well-studied atoms this method could provide a very efficient way to get a detailed overview of its properties. What is more, in future studies the researchers hope to use polarized X-rays to also obtain information about an atom’s spin state, opening interesting possibilities in areas such as spintronics and memory technologies.

Heading image: As the tip was scanned across ten positions in a sample containing two terbium atoms, it picked a signal only from the positions (2 and 9) where terbium was located (left: STM image; right: sketch of the corresponding molecular structure). (Credit: Ajayi et al, 2023)

The First Search Engines, Built By Librarians

Before the Internet became the advertisement generator we know and love today, interspersed with interesting information here and there, it was originally a network of computers largely among various universities. This was even before the world-wide web and HTML which means that the people using these proto-networks, mostly researchers and other academics, had to build things we might take for granted from the ground up. One of those was one of the first search engines, built by the librarians who were cataloging all of the research in their universities, and using their relatively primitive computer networks to store and retrieve all of this information.

This search engine was called SUPARS, the Syracuse University Psychological Abstracts Retrieval Service. It was originally built for psychology research papers, and perhaps unsurprisingly the psychologists at the university also used this new system as the basis for understanding how humans would interact with computers. This was the 1970s after all, and most people had never used a computer, so documenting how they used search engine led to some important breakthroughs in the way we think about the best ways of designing systems like these.

The search engine was technically revolutionary for the time as well. It was among the first to allow text to be searched within documents and saved previous searches for users and researchers to access and learn from. The experiment was driven by the need to support researchers in a future where reference librarians would need assistance dealing with more and more information in their libraries, and it highlighted the challenges of vocabulary control in free-text searching.

The visionaries behind SUPARS recognized the changing landscape of research and designed for the future that would rely on networked computer systems. Their contributions expanded the understanding of how technology could shape human communication and effectiveness, and while they might not have imagined the world we are currently in, they certainly paved the way for the advances that led to its widespread adoption even outside a university setting. There were some false starts along that path, though.

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Hackaday Links: June 11, 2023

As Tom Nardi mentioned in this week’s podcast, the Northeast US is pretty apocalyptically socked in with smoke from wildfires in Canada. It’s what we here in Idaho call “August,” so we have plenty of sympathy for what they’re going through out there. People are turning to technology to ease their breathing burden, with reports that Tesla drivers are activating the “Bioweapon Defense Mode” of their car’s HVAC system. We had no idea this mode existed, honestly, and it sounds pretty cool — the cabin air system apparently shuts off outside air intake and runs the fan at full speed to keep the cabin under positive pressure, forcing particulates — or, you know, anthrax — to stay outside. We understand there’s a HEPA filter in the mix too, which probably does a nice job of cleaning up the air in the cabin. It’s a clever idea, and hats off to Tesla for including this mode, although perhaps the name is a little silly. Here’s hoping it’s not one of those subscription services that can get turned off at a moment’s notice, though.

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A Peek Inside A 747 Fuel Gauge

It isn’t that often that we civilians get the chance to closely examine the fantastic internals that make up the modern marvels of avionic engineering. Luckily for us, [Glen] got his hands on a 747 fuel gauge and tore it down for our benefit. Not only does he tear it down, but he also builds a controller to display values.

Unlike your typical automotive fuel gauge that reports the distance from the top of the tank to the fuel level, this gauge reports the number of pounds of fuel. The fact that the indicator pictured above can go all the way to 95,000 pounds of fuel hits home the sheer scale of the fuel tanks on a 747 compared to your Volvo. Of course, where this gets interesting is the teardown with the metal sleeve removed. A 400 HZ AC servo motor moves the pointer and counter through the gearing with the help of a feedback potentiometer. The resistance tolerance is only 3%, as there are adjustment knobs on the back. But the linearity spec is only 0.06%, putting this part in a different grade from most pots.

One of the indicators was in worse shape than the others, so [Glen] got to work tapping into the internals of the gauge to drive the motor directly. A custom AC power supply repurposed from another project provided power, and a Raspberry Pi Pico was the PID controller. For [Glen], it isn’t all roses. Unfortunately, a noisy spot around 22,500 prevents accurate placement around there.

The code is up on GitHub, and we love having a gauge on the desk to show whatever value we like. If you are curious about more 747 instruments, this retro control unit might interest you.

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Hyundai Is Doomed: Porting The 1993 Classic To A Hyundai Head Unit

In the natural order of the world, porting DOOM to any newly unlocked computing system is an absolute given. This a rule which [greenluigi1] understands all too well, leading to presumably the first Hyundai to be equipped with this all-time classic on its infotainment system. This follows hot on the trail of re-hacking said infotainment system and a gaggle of basic apps being developed for and run on said head unit (being the part of the infotainment system on the front dashboard). Although it is a Linux-based system, this doesn’t mean that you can just recompile DOOM for it, mostly because of the rather proprietary system environment.

To make life easy, [greenluigi1] picked doomgeneric as the version to port. The main selling point of this project is that it only requires the developer to implement five functions to support a new platform, which then ‘just’ left figuring out how to do this on a head unit. Two of these (DG_SleepMs() and DG_GetTicksMS()) could be copied verbatim from the X11/xlib port, but the remaining three required a bit of sleuthing.

Where things go sideways is with keeping the head unit’s Helix window manager happy, and stick to the limited ways a GUI application can be launched, including the way arguments are passed. For the PoC, it was decided to just hardcode these arguments and only register the game with Helix using an .appconf configuration file. When it came to drawing pretty graphics on the screen, this was decidedly easier since the system uses Qt5 and thus offers the usual ways to draw to a QPixmap, which in this case maps to the framebuffer.

After a few playful sessions with the head unit’s watchdog timer, [greenluigi1] found himself staring at a blank screen, despite everything appearing to work. This turned out to be due to the alpha channel value of 0 that was being set by default, along with the need for an explicit refresh of the QPixmap. Up popped DOOM, which left just the implementation of the controls.

In order to start the game, you have to literally buckle up, and the steering wheel plus media control buttons are your inputs, which makes for a creative way to play, and perhaps wear some bald spots onto your tires if you’re not careful. If you’d like to give it a shot on your own ride, you can get the project files on GitHub.

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A wristwatch based on a red PCB with seven-segment LCD screens

The Time Machine Mk. 8 Is A Sleek Smartwatch With Retro Styling

The primary purpose of a wristwatch is to tell the time, which pretty much any watch does perfectly fine. It’s in the aesthetics, as well as features other than time-telling, where a watchmaker can really make their product stand out from the rest. Watchmaker and electronic artist [Eric Min] focused on those two areas when he designed the Time Machine Mk.8, which combines exquisite design with simple, offline smartwatch functionality.

The heart of the watch is a Microchip ATSAMD21G18 low-power 32-bit microcontroller. [Eric] chose it for its high performance, ease of use and large number of integrated peripherals, a real-time clock being one of them. With the basic clock function thus taken care of, he then decided to add several useful sensors: a battery fuel gauge to keep an eye on the 40 mAh rechargeable lithium cell, a three-axis accelerometer to enable motion sensing and an environmental sensor to track temperature, humidity and pressure.

A faux 1980s magazine ad for a red PCB wristwatchThe various functions are operated using four pushbuttons along with a 16-step rotary encoder set in the middle. The overall design of the watch is inspired by Formula 1 steering wheels, as well as various sports cars and media franchises like Neon Genesis Evangelion and Akira. [Eric] considered a few different options for the display but eventually settled on two four-digit seven-segment LCDs, which fit nicely into the retro-futuristic aesthetic of the Mk.8. It’s so retro, in fact, that it almost makes [Eric]’s faux 1980s magazine ad look genuine.

All components neatly fit together on a dual-layer PCB, which is a true work of art in itself. From the lightning bolt on the front to the hidden Frank Sinatra lyrics, it definitely stands out from the crowd of ordinary LCD wristwatches. It’s also quite a step up from [Eric]’s previous watch design, the Time Machine Mk.IV.

Over the years we’ve seen several other examples of how a bare PCB, or even a stack of them, can become a beautiful wristwatch.

Modern Brownie Camera Talks SD And WiFi

If you’re at all into nostalgic cameras, you’ve certainly seen the old Brownie from Kodak. They were everywhere, and feature an iconic look. [JGJMatt] couldn’t help but notice that you could easily find old ones at a good price, but finding and developing No. 117 film these days can be challenging. But thanks to a little 3D printing, you can install an ESP32 camera inside and wind up with a modern but retro-stylish camera. The new old camera will work with a memory card or send data over WiFi.

The Brownie dates back to 1900 and cost, initially, one dollar. Of course, a dollar back then is worth about $35 now, but still not astronomical. After cleaning up and tuning up an old specimen, it was time to fire up the 3D printer.

There are also mods to the camera to let it accept an M12 lens. There are many lenses of that size you can choose from. There are a few other gotchas, like extending the camera cable, but it looks like you could readily reproduce this project if you wanted one of your very own.

We’ve seen old cameras converted before. Or, you can just start from scratch.