The scientists measure their results in nanometers, equal to one billionth of a meter, and micrometers, equal to one millionth of a meter. The scientists started with two parallel gold nanostructures on a silicate substrate. Those structures were formed by electron-beam lithography, one of several widely used nanoscale construction techniques. Because the scientists knew the size and spacing of the initial structures and the thickness of the layers of films created by the molecules atop the structures, they could calculate the size of the narrowing space between the structures.
Scientists use the resulting space for forming even smaller wires by filling the space with gold.