An easy-to-implement filter for separating photo-excited signals from topography in scanning tunneling microscopy

摘要: In order to achieve elemental and chemical sensitivity in scanning tunneling microscopy (STM), synchrotron x-rays have been applied excite core-level electrons during tunneling. The x-ray photo-excitations result tip currents that are superimposed onto conventional currents. While carrying important physical information, the varying induced can destabilize feedback loop causing it be unable maintain a constant current, sometimes even retract fully or crash. this paper, we report on an easy-to-implement filter circuit separate from currents, thereby allowing simultaneous measurements of topography contrasts. schematic presented here also other variants light-assisted STM such as laser STM.