Evidence of positronium Bloch states in porous crystals of Zn₄O-coordination polymers

Dhanadeep Dutta, Jeremy I. Feldblyum, David W. Gidley, James Imirzian, Ming Liu, Adam J. Matzger, Richard S. Vallery, and Antek G. Wong-Foy

Accepted Friday Apr 19, 2013

Positronium (Ps) is shown to exist in a delocalized state in self-assembled metal-organic crystals that have large 1.3-1.5 nm cell sizes. Belonging to a class of materials with record high accessible specific surface areas, these highly porous crystals are the first to allow direct probing with simple annihilation lifetime techniques of the transport properties of long-lived triplet Ps in what is hypothesized to be a Bloch state. Delocalized Ps has unprecedented (high) Ps mobility driven primarily by weak phonon scattering with unusual and profound consequences on how Ps probes the lattice.