Findings
Although positron-binding atoms and molecules are at the heart of biomedical technologies such as positron emission tomography (PET) and for materials characterization techniques such as positron annihilation lifetime spectroscopy (PALS), relatively little is known about the bound quantum states of such matter-antimatter complexes.
Direct experimental observation is made difficult by their short lifetime, on the order of nanoseconds, and theoretical calculations of the positron-binding energy of atoms and molecules are notoriously challenging due to electron-positron and electron-electron correlation.
In this work, Aurbakken and co-workers propose ultrafast spectroscopy for the detection of positronium chloride, PsCl. The paper provides a detailed description of time-dependent Hartree-Fock theory for electron-positron systems based on the discrete variable representation, eliminating basis-set incompleteness errors. This methodology is used to predict that ultrafast positronic above-threshold ionization spectra of PsCl should be clearly identifiable in a background of positronium spectra, at least in the multiphoton regime.
Published, 28th August 2026: