Lawrence Berkeley National Laboratory

Specimen charging may be one of the most significant factors that contribute to the high variability generally low quality of images in cryo-electron microscopy. Understanding the nature of specimen charging can help in devising methods to reduce or even avoid its effects and thus improve the rate of data collection as well as the quality of the data. We describe a series of experiments that help to characterize the charging phenomenon which has been termed the Berriman effect. The pattern of buildup and disappearance of the charge pattern have led to several suggestions for how to alleviate the effect. Experiments are described that demonstrate the feasible of such charge mitigation.