Electron microscopes may have reached resolution limit

Nature : Attempts to build electron microscopes of increasingly higher resolution have encountered a source of noise that they may not be able to overcome. In 2008 researchers from Lawrence Berkeley National Laboratory in Berkeley, California, unveiled a microscope with a resolution of 0.5 Å, twice as fine as the previous best. Their attempt to surpass that success included a blur correction device that they expected would allow them to reach 0.33 Å. They found instead that the resolution wasn’t even as good as their original machine. The investigation into what caused the drop in resolution began in 2010. Engineers at Corrected Electron Optical Systems (CEOS) in Heidelberg, Germany, who built the blur corrector have finally determined the problem. Thermal vibrations in the device materials were causing electrons in them to oscillate. The oscillations created magnetic fields that interfered with the electron beam of the microscope. Because all electron microscopes currently use blur correction devices, until blur correction can be handled differently, the microscopes are limited to a resolution range of 0.45 to 0.75 Å.