A sense of new beginnings in positron and positronium chemistry

Abstract

This has been the most future-oriented workshop in my memory. Many participants are thinking about the next experiments to perform, new phenomena to study, and new parameters to measure. We look forward to new optical correlations, both with exciting radiation and intrinsic fluorescence. We very badly need positron and positronium binding energies to atoms, molecules, and radicals. We very badly need work functions, band gaps and edges, and trap depths for positron and positronium in molecular liquids and solids. The binding energies of positronium itself in various molecular materials is an important and poorly understood quantity. New data presented at this workshop on the energy of positronium at its formation, and its thermalization time, are most significant,3 and we look forward to refinements in those measurements and in their interpretation. We need to understand the thermalization times of positrons much better than we do. The role of voids and/or surfaces in positronium formation needs to be illuminated, including numerical estimates and measurements for the cross section of this most important process.