Fabrication of a glass-coated metal tip for synchrotron-radiation-light-irradiated scanning tunneling microscopy

A method to fabricate a glass-coated tungsten tip and the performance of the tip in scanning tunneling microscopy (STM) under irradiation of the synchrotron radiation light are reported. A tungsten tip was first coated with glass, and then the glass layer on the tip apex was removed by a focused ion beam. The bare area of the tip apex is less than 5μm in length. Using the tip, atomically resolved STM images were obtained in ultrahigh vacuum conditions without significant contaminations. STM studies under the irradiation revealed that the coating is effective in blocking photoinduced electrons impinging on the sidewall of the tip and in extracting photoelectron current emitted from a small area below the tip apex.