American Physical Society Focus August 2, 2019
It is long assumed that light hitting a metal surface at an angle pushes on the free electrons, moving them forward. A team of researchers in the US (NIST, University of Maryland, Brown University) aimed an infrared laser toward the metal surface at a glancing angle and placed an electrode at the far end of the metal sample to detect any voltage created if the light drove the electrons along the metal, which would create an excess of negative charge at the far end. As they varied the angle, the team measured a voltage that largely agreed with theoretical expectations based on the simple light-pushing-electrons picture. However, the voltage they measured was the opposite of that expected, implying that the current flow was in the wrong direction. Experiments with the metal exposed to air showed the light pushed the electrons forward. The effect lies at the basis of efforts to engineer delicate light-metal interactions in nanophotonics devices…read more. TECHNICAL ARTICLE
New results clearly demonstrate that researchers don’t fully understand what happens when light hits a metal surface. Credit: UC San Diego Jacobs School of Engineering