In the past, scientists tried to make out atoms by increasing the power of microscopes, but modern physicists have a different approach. The British Council of Physics and Engineering has named a photograph by David Nadlinger entitled “A Single Atom in an Ion Trap” as the winner of a photography competition from the world of science. The photo shows a single strontium atom, and it can really be seen with the naked eye, but with one caveat.
Strontium was chosen as the atom donor for the shot because of its size. In this element, the atom has an impressive nucleus of 38 protons, which is why its diameter is about 0.1 nanometer. This is still infinitely small to see with the human eye, so physicists went for a trick and sent a powerful laser beam at the atom. Its energy excited the strontium electrons, they began to glow brightly, which allowed an ordinary camera to record this light in the form of a dim but visible point.
In fact, in the picture we see not the atom itself, but the light emanating from it, but this does not contradict the principles of physics. Since a blue-violet laser was used, then you need to look for a dull blue dot in the photo, it is located approximately in the middle between the emitters of the electromagnetic field that holds the atom in place. However, there is a nuance – the photographer had to use a very long exposure in order to accumulate enough light to fix it. The human eye cannot repeat this, so it is still problematic to observe an atom live, although the picture itself makes a strong impression and will certainly go down in history.