Optimizing the environment for sub-0.2 nm scanning transmission electron microscopy

Sub-0.2 nm probes can now be readily obtained on Schottky field-emission mi croscopes. However, environmental instabilities are proving to be the limit ing factors for atomic resolution spectroscopy and distortion-free annular- dark field imaging. This is a result of the long acquisition times and the serial nature of the scanning system where instabilities result in image di stortions rather than reductions in contrast. Troubleshooting the most comm on environmental problems is discussed here. In addition to the expected se nsitivity to mechanical vibration, electromagnetic interference and tempera ture variations, air-pressure fluctuations are found to have a significant impact on microscopes with side-entry goiniometers.