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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

by mohn 9y ago

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-we-could-see-it-with-our-naked-eye-what-would-it-look-like https://www.quora.com/If-an-atom-could-be-enlarged-such-that...

mncharity 9y ago
> 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.
- mohn 9y ago
  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.
  - mncharity 9y ago
    > 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 ...". :)

by mohn 9y ago

mncharity 9y ago

> 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.

mohn 9y ago
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.
- mncharity 9y ago
  > 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 ...". :)