The Zeiss GeminiSEM 450 is a high-performance variable pressure Scanning Electron Microscope (SEM) equipped with a Schottky type field emission gun, various detectors (in-lens and Everhart-Thornley type secondary electron detectors, as well as a variable pressure secondary electron detector, an in-lens back scattered electron detector, and multi-quadrant solid state back-scattered electron detector). In addition, there is a detector for energy-dispersive x-ray analysis. This system has an oil free vacuum system to maintain hydrocarbon free imaging. To ensure the clean environment, the SEM is equipped with an in situ reactive oxygen sample cleaning system.