10 ms·
This is an insanely cool picture. Some quick napkin math (please let me know if I'm way off base here): in the second pic, the electrodes are ~74 pixels apart
by dgritsko 9y ago
This is an insanely cool picture.
Some quick napkin math (please let me know if I'm way off base here): in the second pic, the electrodes are ~74 pixels apart and the strontium atom is ~2 pixels wide.
The electrodes are ~0.078 inches apart, so these 2 pixels represent ~0.0021 inches (or ~0.05334 mm).
Google tells me that the Van der Waals radius of a single strontium atom is 255 pm.
So the diameter of the actual atom is something like 10,000x smaller than the space represented by these pixels. Crazy!
- semi-extrinsic 9y agoI guess it's basically a point source compared to the camera resolution, so what you're seeing as the "atom size" is the diffraction limit of the camera lens.
- theandrewbailey 9y agoI was just thinking that the atom has to be letting off (reflecting) some serious quantity of light in order for just one to appear with off the shelf camera equipment.
- thinkloop 9y agoI still don't get it, 10,000 times more light than its size?
- 21 9y agoThey say it was a long exposure. The atom was illuminated and irradiated light for a long enough time to register on the sensor.
- thinkloop 9y agoEven 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).
- brazzledazzle 9y agoMaybe it's light reflected by the atom at multiple points? The article mentions that it's "held nearly motionless" but over a long exposure perhaps the degree of movement allowed created a composite large enough to show up in the photo.
- ars 9y agoNo, that's not it. Just because it is small, doesn't make it invisible. You can't see single atoms because they normally don't send any light toward you. But if they did, and this one is, you would see that light. You aren't seeing the atom exactly, you are seeing what it sends toward you, and the human eye can see single photons. (And so can cameras.)
- albedoa 9y ago> No, that's not it. That has to be at least partially it for the rest of your comment to be right (which it is!). To say the atom was "held nearly motionless" is to say it moved a little during the exposure. It sent the light toward the sensor from all of its positions.
- ars 9y ago> That has to be at least partially it No, not at all. The wavelength of the light is about 1,500 times larger than the atom emitting it. So the atom would need to move at least 1,500 diameters to make any difference in the light. It doesn't move that much.
- ars 9y agoAnalyze this photo instead: http://content.assets.pressassociation.io/2018/02/11175054/f7f7c86b-dc52-4355-a622-9e3cb9a876fc.jpg http://content.assets.pressassociation.io/2018/02/11175054/f...
- Jedd 9y agoWhile the manual for my DSLR doesn't specifically refer to this use case, reading between the lines it sounds like using a jpg encoding for atomic-scale image capture isn't recommended.