Positron annihilation in triphenylphosphine oxide complexes: Positronium inhibition mechanism involving excitation of charge transfer states

Positronium formation in triphenylphosphine oxide and its lanthanide and hydrogen peroxide complexes was characterized. The low positronium probability formation was attributed to a mechanism involving a competition between charge transfer at large distances, induced by the positron-molecular electron interaction, and the positronium formation during the positron molecule scattering.