Submicron-Resolution Study of a Thin Ni Crystal Using a Brightness-Enhanced Positron Reemission Microscope

Abstract

A 1500-Å Ni(100) film is back illuminated with 5-keV positrons from a brightness-enhanced slow positron beam. Some of the positrons diffuse through the film and are emitted from the front surface by virtue of the Ni having a negative positron affinity. An immersion objective and projector lens form a 1150× image of the reemitted positrons at a 2D position-sensitive detector. With a resolution of 3000 ± 1000 Å we observe patches attributable to positron trapping at boundary layers inside the film. The advantages and ultimate capabilities of the positron reemission microscope are also discussed.