E-Mail IMAGE: An illustration depicting a topological surface state with an energy band gap (an energy range where electrons are forbidden) between the apices of the top and corresponding bottom cones (allowed... view more Credit: Dan Nevola, Brookhaven National Laboratory UPTON, NY--Electrons in a solid occupy distinct energy bands separated by gaps. Energy band gaps are an electronic "no man's land," an energy range where no electrons are allowed. Now, scientists studying a compound containing iron, tellurium, and selenium have found that an energy band gap opens at a point where two allowed energy bands intersect on the material's surface. They observed this unexpected electronic behavior when they cooled the material and probed its electronic structure with laser light. Their findings, reported in the