Hacker News new | comments | show | ask | jobs | submit login
Picture of Single Trapped Atom Wins UK Science Photography Prize (gizmodo.com)
57 points by evo_9 10 months ago | hide | past | web | favorite | 17 comments

Years ago, someone created a similar picture with a single atomic nucleus. I'd like to find it again.

Normally, nuclear transitions are invisibly-high energies. X-ray and gamma. But a couple of nuclei have multi-step spin isomer decays (or was it shape isomer?). One step of which is visible. So someone trapped and fully stripped a nucleus, and bombarded it to visibility. Naked-eye visibility. And took a picture. Of vacuum vessel window, with a green(?) fluorescence dot.

I saw that picture years ago. Likely a cover photo on something.

I would very much like to find it again. For use in educational content. A lot of time has been spent looking for it, both by myself, and a couple of MIT science librarians. If anyone has a clue, I'd very much appreciate it. Here is a mockup[1] I gimped for user testing.

Why use it in education? To make the concept of atoms more concrete. Atomic electrons are too small (and slow and fragile) to see with your naked eye. But (a couple of) nuclei you can (under hard-to-contrive conditions). Absent concrete, students build their understanding of materials on muddy misconceptions. For example, one failure-mode in teaching high-school stoichiometry, is students not thinking of atoms as real physical objects.

And to preempt a common response... one professor complained "you aren't really seeing the nucleus - it's only a diffraction dot"... right before they headed out to a star party, to apparently "not see" stars. ;)

[1] http://www.clarifyscience.info/assets/2017-Atoms/assets0/wk/...

The image in David Wong-Campos' Quora answer [1] is a bit different than what you've described, but maybe it would have similar educational use. David says the image was made with a long exposure time, but that it's (faintly) visible with the naked eye.

It's from an ion trap in Chris Monroe's lab at the Joint Quantum Institute. I assume that if they had stripped all the electrons off the barium atom, they'd probably call it a "nucleus" instead of just an "ion".

[1] https://www.quora.com/If-an-atom-could-be-enlarged-such-that...

> maybe it would have similar educational use. [...] it's (faintly) visible with the naked eye.

Indeed! It's nifty to hear of an atomic naked-eye visibility story with provenance. Thanks!

"Atoms are 'too small to see' (it is said)... but not really"' stories are liked.

One of the linked papers has the illuminating laser as ultraviolet (thank you sci-hub[1] - making science part of life), so that's definitely electron transitions, not nuclear ones. I'd expect an X-ray laser to be bigger-than-room sized. And I don't know if gamma-ray laser equipment exists yet.

Nuclear shape-isomer transitions are literally the nucleus changing shape. Say between hugged and non-hugged beach ball shape. They're different energy levels, so the nucleus emits a photon to balance. It squeaks. Squeaks a blink.

I don't remember whether the visible transition was a shape-isomer or a spin-isomer transition. But that emitted photon, is usually an invisible gamma-ray or X-ray photon. A few oddball nuclei, toss out an extra (visible low-energy) photon. So if you hit one of these nuclei with a high-energy photon, it changes shape (or was it spin?), it then quickly changes back, giving you back a very-slightly-lower high-energy photon, and a second, visible photon. And then you do it again. So very quickly (nuclear-time-scale very quickly), that a single nucleus can generate enough visible photons, that it can be seen naked-eye. Seen through a gamma-/X-ray-blocking piece of glass, so you don't lose that eye.

[1] Regards sci-hub, that's one point which didn't come up in the recent sci-hub thread. Often when creating education content, I don't need to actually read a paper - I'm just searching for some little bit of information, that's not in the abstract (often it's in the introduction, or mentioned elsewhere in passing), and am thus stymied by paywalls. Imagine trying to do a google search, with no blurbs, and each link you click costs tens of dollars. Until sci-hub.

Nuclear physics is not my forte, but if spin is to be conserved, wouldn't there need to be a spin-isomer transition: one photon in, two photons out --> spin quantum number of nucleus must change to balance?

I think one good way to narrow your search would be to identify a single candidate element (or a few) that has such a "forbidden transition" where, despite being forbidden, the time constant is still quite short (so you can get a lot of light out of repeated excitation of a single nucleus) and the energy gap that gives rise to one of the photons is a mere 1.5~3.5 eV (visible).

With a good searchable database of nuclear isomer energy levels, it should be possible to identify transitions like these, and if only a few elements have them, you can start including those names in the search and maybe get results that point more in the right direction. Or do you already have the names of some of those oddball nuclei you mentioned?

I haven't found a good searchable database, just an ugly scanned PDF of Kocher's "Radioactive Decay Data Tables" (1981). Maybe someone has published a more computer-searchable version of the data since then.

> Nuclear physics is not my forte ... [spin conservation consequences]

And very not mine - sorry.

> database of nuclear isomer energy levels [-> identify element(s) -> improve search odds]

A good idea. My extremely fuzzy recollection is the two-ish were stable-ish mid-weight elements. But it's been a long time.

Thank you for the suggestion. If I go down this path again (for a WebVR page to teach size/scale?), I may try that. Another possibility is to find and ask more people with a related research focus. I'd just hoped that with a relevant HN thread, someone might reply "oh, sure, that's on my shelf; let's see, it's ...". :)

Technically, it is not the picture of an atom. The wavelength of light is way too big for atoms. The picture is about the photons emitted by the atom after photo-stimulation. But anyway , one of the coolest pictures I've ever seen.

Technically, pictures always represent the light emitted or reflected off objects, not the objects themselves (hence photo-graphy, "drawing with light").

However I agree that "Picture of light emitted just by a single trapped atom" would be a more accurate title and yet still incredibly cool.

First, reflection and emission are not the same. But more importantly, the only sensible definition of "seeing an object" is that the angular distribution of the light entering your eyeball carries some information about the geometric shape of the object. Otherwise, we could just as correctly say that when we look at dog we are seeing the sun or the overhead florescent bulbs; that's where the photons came from. Likewise, if I put a piece of strongly frosted glass between me and the dog, it would be misleading to say I can "see the dog" even if the photons that come from the dog reach my eye. The key reason this is wrong is that strongly frosted glass scrambles the information.

>Otherwise, we could just as correctly say that when we look at dog we are seeing the sun or the overhead florescent bulbs; that's where the photons came from

No, they didn't. The energy came from the sun, however the photons which are collected in your retina to form the image of a dog were emitted from the dog itself. "Reflection" is just the stimulation of photon emission via radiation.


You're gesturing at an unconvincing objection: that there is no difference between reflection and emission because there is a sense in which light passing through matter is continuously being absorbed and re-emitted. (I say "gesturing" because you don't actually know the physics; it is completely different than either stimulated emission or the photoelectric effect, which you could tell by reading the Wikipedia articles.) Explaining why this objection is boring and unconvincing would ultimately be a long discussion in the philosophy of science ("how can we keep using folk terminology that presumes a sharp devision between two concepts when a theory of physics suggests they are actually just part of a continuum?"), but you can get a sense of that by noticing that emission generally involves a change in the frequency of light while reflection does not.

> Technically (...) The picture is about the photons

Technically, all pictures are about photons.

For the images to human interface, sure. But you can use pretty much anything small and fast enough to take pictures - neutrons, neutrinos, various ions, phonons...

Now, taking photos is inherently photon/E&M based.

It's as much a picture of an atom as a picture of an energized light bulb filament is a picture of a light bulb filament. I don't think anyone would say the latter is "technically" not what it is.

Link to previous discussion: https://news.ycombinator.com/item?id=16362085

Very cool, I couldn't find in the text what is the scale of the picture ?

> Nadlinger’s grand prize photo shows an atom as a speck of light between two metal electrodes placed about 2mm (0.078in) apart.

From https://petapixel.com/2018/02/12/picture-single-atom-wins-sc...

The gap from one electrode to the atom is 2 mm. So, the total gap is 4 mm.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact