Unexpected secondary electron imaging contrast at low vacuum with the environmental scanning electron microscope ESEM

This poster shows exemples for secondary electron SE-imaging contrast due to partial electrical charging on the sample. The ESEM allows to control the chamber pressure and thus the degree of partial charging between areas of different electrical conductivity. Due to the SE-imaging capabilities of the ESEM at these relatively high pressures of 0.5-20 torr (compared to HV conditions) the charge induced SE-contrast corresponds to a material contrast not available in BSE or EDX mode. The examples shown are: ink on paper, graphite on paper and emaile-metal interfaces.