By carefully analyzing the
reflected beam, the researchers detected stripes of holes lying along every eighth row of copper
atoms, as they describe in the 4 March issue of Physical Review Letters.
The technique, developed
by researchers at Sheffield University, uses the phenomenon of laser «speckle»: no surface is uniformly smooth at the atomic scale and, when laser light
reflects off it, the roughness caused
by the individual
atoms creates interference in the wavefronts so that the
reflected light seems to scintillate, with tiny bright and dark patches.