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 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. ;)
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".
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 - 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.
 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.
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.
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 ...". :)
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.
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.
Technically, all pictures are about photons.
Now, taking photos is inherently photon/E&M based.