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Picture of a Single Atom Wins Science Photo Contest

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Re: Picture of a Single Atom Wins Science Photo Contest

#81
post #61

Earlier quoted context omitted.

You're not looking directly at the atom itself (which is impossible... atoms are smaller than light's wavelength). You're looking at the photons emitted by an excited atom, as collected over an extremely long exposure by the camera's sensor. Which will resolve to ~1px in size... the smallest unit the camera can image.

It doesn't really mean anything to day "you aren't looking at it , you're looking at the reflected photons". You're always looking at reflected photons of everything.

Actually “reflected” doesn´t mean much for photons: they are absorbed and re-emitted.

Re: Picture of a Single Atom Wins Science Photo Contest

#82
post #81

Earlier quoted context omitted.

It doesn't really mean anything to day "you aren't looking at it , you're looking at the reflected photons". You're always looking at reflected photons of everything.

Actually “reflected” doesn´t mean much for photons: they are absorbed and re-emitted.

Isn't that what "reflected" means?

Re: Picture of a Single Atom Wins Science Photo Contest

#84
Photographer here. The amount of attention this has received has caught me a bit off guard – this is really just a somewhat pretty picture of what is a standard technique in physics by now.

I'm putting together a short post with answers to some of the most commonly asked questions, but in the meantime, check out this great comment by a well-informed Redditor:

https://www.reddit.com/r/interestingasfuck/comments/7x4o27/p...

Re: Picture of a Single Atom Wins Science Photo Contest

#85
post #81

Earlier quoted context omitted.

Actually “reflected” doesn´t mean much for photons: they are absorbed and re-emitted.

Isn't that what "reflected" means?

Not exactly.

https://en.m.wikipedia.org/wiki/Reflection_(physics)

For most of the history of the word “reflect”, its meaning was definitely not “absorb and re-emit photons of the same frequency”.

Re: Picture of a Single Atom Wins Science Photo Contest

#86

Earlier quoted context omitted.

Even if the exposure were for a year, if the amount of light being emitted is less than the hardware can perceive, it wouldn't register - hence the need for electron-microscopes and such. There's a story here about the size of the light being emitted that doesn't seem satisfactorily answered (not by you, the article and stuff in general).

CCDs can detect single photons. It isn't much of a challenge. I would be suspicious that the surrounding apparatus is Photoshopped in from a separate exposure.

Nope, not photoshopped. It's a single exposure; the apparatus is illuminated using flashes.

The latter made lighting the shot in a controlled fashion a bit easier than if I had used continuous sources – you'd be looking at using a torch with a bunch of filters or a computer monitor on the lowest brightness otherwise.

Re: Picture of a Single Atom Wins Science Photo Contest

#87
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/...

Re: Picture of a Single Atom Wins Science Photo Contest

#88
post #15

Earlier quoted context omitted.

That explanation doesn't really satisfy. Perhaps, based on a large body of experimental evidence, it is known that the number of atoms present can be determined by the apparent brightness. Perhaps it's something totally different. Regardless, it would be helpful if the author/photographer/somebody explained the rationale that makes them confident that this is only a single atom.

Isn't hard to figure out when you've only got one ion in the trap: https://www.physik.hu-berlin.de/de/nano/lehre/quantenoptik09... Heck, you can line up ions in a row and take pictures of those if you'd like.

Just because my previous comment is now gone: It's nice to mark PDFs
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