According to this BGR.com article (also carried by Yahoo.com), a photographer allegedly photographed a Strontium atom held in suspended animation between two electrodes supposedly exciting the atom causing it to glow. if you blow up this picture, you can see a speck of something, but I seriously doubt it is ONE atom.
The article lacks explanation how we can see an image of one atom - even if it is emitting light by being excited by lasers. Note: The scale of the of smallest thing we can see, visible light, is in the realm of nanometers (1x10^-9 meters) vs. the scale of the size of the Strontium atom is in the realm of picometers (1x10^-12 meters). That means the atom is in the ballpark of 1,000 times smaller than what the minimum the human eye can detect.
Sure, we see the manifestation of excited atoms all the time. But, seeing one atom au naturale? What’s the whole story here, Straight Dopers?
The photograph is magnified substantially. The distance between the electrodes is actually 2 mm according to this. In other words, the equipment looks like it’s “actual size” but it isn’t, and the atom isn’t actual size either. You’re also not actually seeing the atom; you are seeing refraction of a laser from the atom.
To be clear, when you say “refraction of a laser”, you mean we’re seeing the deflection of a laser beam due to the presence of the atom. So, it could be said we are seeing a hole in the laser beam created by this deflection…magnified for the camera to record.
By this standard, you’re never seeing atoms, just light reflecting off (or refracting through, or similar) atoms.
This is an atom in an ion trap which is re-transmitting light shone onto it by a laser. It is a single atom, and it is re-transmitting visible light. Saying you’re seeing light and not an atom is a few shades too pedantic for experts to credit.
You know how when you look at a really bright light source, the ‘glow’ is much bigger than the bulb itself? I think that’s what is happening here. I mean, that dot is still way larger than the atom itself. It’s just that the atom is being energized strongly and it’s emitting a ton of photons, and you’re seeing those photons.
You can take images of atoms indirectly, through measuring the electric potential of their electron clouds with high end microscopes. This results in an image where you can in fact “see” the molecules correctly down to the individual atoms on the surface.