A photograph showing a single atom has won a science photography contest. David Nadlinger achieved the shot primarily through patience and planning rather than gadgetry.
The atom appears in the dead center of the photo: it’s the tiny purple dot in a black space with a pointy tip on either side. These tips are electrodes, two millimeters apart, that are suspending the atom in mid-air.
It’s an atom of strontium, a metal with similar properties to calcium. It was previously widely used in the process of extracting sugar from molasses and in the production of cathode ray television sets. Today its main uses are in radiotherapy for cancers that have spread to bones and in fireworks for its dramatic red appearance when burning.
The purple (or rather blue-violet) color of the atom in the photo isn’t from burning but instead because that was the color of laser needed to produce the shot. Nadlinger discovered that the atom absorbed light particles of that color and then re-emitted them for just the right period of time to be captured by a long-exposure photograph.
The pic was taken with an ordinary camera through the window of an ultra-high vacuum chamber that was needed to hold the atom in place. Nadlinger’s only specialized photographic equipment was an extension tube to increase the lens’s focal length.