High intensity perrhenate anion (ReO4−) emitters

Various materials have been investigated for ReO4− (perrhenate anion) emission with the goal of producing a high output emitter for application as a primary ion source in secondary ion mass spectrometry (SIMS) analysis. A new emitter consisting of Re powder/BaSO4 packed in Pt tubes has been found to have superior properties. This system produces in the order of 200 nA/mm2 for over 100 h when heated between 1100 and 1300 °C. Total currents of over several hundred nano-amperes have been sustained (three orders of magnitude higher than previous emitters, >100 h). Lower currents (5–100 nA) persist for hundreds of hours. These emitters have been used in several SIMS guns for over a year, and have proven to be extremely reliable and relatively easy to operate. As the ReO4− ion has previously been shown to be a highly effective projectile for many SIMS applications, the development of this improved high output emitter makes it feasible to extend the range of its application to imaging and depth profiling. [Copyright &y& Elsevier]