For a beam-sensitive specimen, the spatial resolution of TEM analysis is limited by radiation damage, and it is obviously a good thing to minimize the amount of damage that occurs during a measurement. Knock-on displacement damage, which predominates in metals, can be reduced by lowering the accelerating voltage (ideally below a threshold value that depends on atomic weight and displacement energy). Ionization damage (radiolysis), which predominates in organic materials, is often ameliorated if the specimen is cooled below room temperature.