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Picture of a Single Atom Wins Science Photo Contest

petapixel.com

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Re: Picture of a Single Atom Wins Science Photo Contest

#61

Post by tjohns »

4mitkumar wrote: post #60

Why does the atom look so big in the bicture? Atomic radius of Strontium is 219 pm, so that small spec there in the picture should be about 438 pm across. I'm assuming the two ball-pen nib shaped structures on both sides of the spec in the picture are "two metal electrodes placed about 2mm (0.078in) apart". So, the space between the left tip of the electrode and left edge of the spec is about 1 mm. Based on some "vis…

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.

Re: Picture of a Single Atom Wins Science Photo Contest

#62

Post by SeanLuke »

tjohns wrote: post #61
4mitkumar wrote: post #60

Why does the atom look so big in the bicture? Atomic radius of Strontium is 219 pm, so that small spec there in the picture should be about 438 pm across. I'm assuming the two ball-pen nib shaped structures on both sides of the spec in the picture are "two metal electrodes placed about 2mm (0.078in) apart". So, the space between the left tip of the electrode and left edge of the spec is about 1 mm. Based on some "vis…

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 appear that the atom is 1 pixel, but is in fact quite a bit larger than this: there are lots of elements in the image which are significantly smaller than it. So what gives?

Re: Picture of a Single Atom Wins Science Photo Contest

#63

Post by tjohns »

SeanLuke wrote: post #62
tjohns wrote: 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 appear that the atom is 1 pixel, but is in fact quite a bit larger than this: there are lots of elements in the image which are significantly smaller than it. So what gives?

Possibly diffraction, possibly JPEG artifacts, possibly camera movement. Tough to say without more details.

Looking at it, my suspicion is diffraction. But I don't know enough optics to be sure.

Re: Picture of a Single Atom Wins Science Photo Contest

#65

Post by disposablename »

lighttower wrote: post #55
granto wrote: post #46

View it here in actual life size on your display. http://beta.lifesizer.com/view?user=5&ref=_59&h=1080&w=1920 Edit: based on seeing it in actual size, I would say it would be hard to see it with the naked eye, that said as pointed out in other comments, I suppose not impossible if a human eye can detect a single photon.

Thanks for the link. Very cool. What are some use cases for this service?

Mostly dickpics

Re: Picture of a Single Atom Wins Science Photo Contest

#66

Post by gji »

SeanLuke wrote: post #62
tjohns wrote: 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 appear that the atom is 1 pixel, but is in fact quite a bit larger than this: there are lots of elements in the image which are significantly smaller than it. So what gives?

I used to work on trapped ion experiments, and the limitation of the atom size was always the diffraction limit, which is limited by the NA of the lens (f-stop in camera terms) and the wavelength of light. In this case, the optical system (I'm guessing a camera lens) is designed for multiple wavelengths, so it might not reach the diffraction limit at the emission wavelength, which is like 400nm. In that case, the limit would be the aberration of the camera lens, which can be wavelength-dependent. Most camera lenses aren't designed for 400nm light, which is marginally visible.

Re: Picture of a Single Atom Wins Science Photo Contest

#67

Post by amenghra »

sxates wrote: post #19

I'm curious to know how they managed to get a single atom there in the first place. I'm assuming it's not with atomic tweezers?

I don't know in this particular case, but in the late 80s, IBM figured out how to move individual atoms (see https://en.wikipedia.org/wiki/IBM_(atoms)).

Re: Picture of a Single Atom Wins Science Photo Contest

#68

Post by kevin_thibedeau »

thinkloop wrote: post #34
21 wrote: post #33

Earlier quoted context omitted.

They say it was a long exposure. The atom was illuminated and irradiated light for a long enough time to register on the sensor.

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.

Re: Picture of a Single Atom Wins Science Photo Contest

#69

Post by simooooo »

ars wrote: post #58
BuildTheRobots wrote: post #44

Earlier quoted context omitted.

If we're seeing the single photon emitted by a single atom, then how much larger is the spot of light in the image compared to the atom that emitted it? Why isn't there a ruler somewhere in the picture? My brain is absolutely failing to make sense of the scales and sizes in this image.

> then how much larger is the spot of light in the image compared to the atom that emitted it? The atom is about 255 picometers, the light is around 400 nanometers. That makes the light around 1500 times larger than the atom. (Which also helps explain why visible light can not distinguish atoms placed close together - it's so much larger than them.) > Why isn't there a ruler somewhere in the picture? My brain is abso…

Doesn't it just come down to the size of a pixel in the CCD of the camera? Any photons would have to be rounded up to that size.

Re: Picture of a Single Atom Wins Science Photo Contest

#70

Post by cantrevealname »

The article is about seeing a single atom; it's possible to see a single photon too, as was previously discussed on HN:

People can sense single photons: Experiment suggests that humans are capable of perceiving even the feeblest flash of light [1][2]

[1] http://www.nature.com/news/people-can-sense-single-photons-1...

[2] https://news.ycombinator.com/item?id=12163109

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