NEGATIVE ION IMAGING IN FIELD ION MICROSCOPY

Field ion microscopy with negative ion imaging has been successfully performed using organic image gases of high electron affinity such as tetracyanoethylene (TCNE). Pure ion images without contributions from field electrons are obtained in a rather broad range of field strengths since field electron emission is suppressed by the field induced formation of a polymer layer from image gas molecules. Under condensation of TCNE on the field cathode surface, unusual ring structures are observed in the ion image. The origin of these structures is not yet clear