

First Picture of an Atom's Shadow - loki_dx
http://news.nationalgeographic.com/news/2012/07/120710-first-picture-atom-shadow-photograph-science-nature-smallest/

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TheAntipodean
This may be a dumb question but what does the shadow fall on for the
scientists to take a picture of it? If is is landing on the 'lens' then
wouldn't 'silhouette' be a more appropriate term?

As far as I understand all matter is made of atoms so at the atomic level
there wouldn't really be matter (wall, ground etc.) for the shadow to be cast
on.

Amazing nonetheless.

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bmuon
It took a little googling. Here's a potential answer.

The paper the article is based on talks about "absorption imaging". Googling
that I found another paper [1] in ArXiV which describes the method a little
bit: "absorption imaging, where the attenuation of a laser beam passing
through an atom cloud is measured, is the workhorse of ultracold atom
experiments. The shadow cast by the atom cloud onto the CCD allows an
estimation of the atomic column density."

And if I understood correctly, a CCD is a "charge-coupled device" [2], sort of
a digital camera. And that's where the shadow falls.

[1] <http://arxiv.org/pdf/1101.4206v2.pdf> [2]
<http://en.wikipedia.org/wiki/Charge-coupled_device>

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icebraining
The paper at arXiv: <http://arxiv.org/abs/1201.5280>

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aarondf
Enhance it.

<http://www.youtube.com/watch?v=Vxq9yj2pVWk>

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sp332
These are terrible, but really funny
<https://www.youtube.com/watch?v=KUFkb0d1kbU>

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3rd3
So, what do we actually see on the photo? Is the black dot a shadow of the
nucleus or a shadow of the electron shell? And these ripples are effects or
the wave properties of light?

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femto
I'd also be curious about the effects of diffraction and whether the atom
appears as a sphere. If so, can we expect to see a Poisson spot, which a
bright spot in the middle of the shadow caused by constructive interference?

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mnl
Actually it appears to be the spatial pattern of absorption of around 6
million photons. So technically it is a shadow, but it's not like you are
flashing an atom from the right and taking a picture from above. I'd like to
know more about Fresnel lens aberrations to have an opinion about the
feasibility of such a measure.

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itsybaev
Interesting. When I read the title, I was curious about the practical use of
that photo until I read that this would lead to study DNA inside living cells.

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Monkeyget
I don't quite understand the how nor the consequences. How does this compare
to crystallography?

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fghh45sdfhr3
You could use this for things that don't crystallize. It might even be easier
to reproduce than crystallizing for things that can.

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markwong
reminds me of Dune II

