Positron annihilation and binding in aromatic and other ring molecules

Abstract

Annihilation spectra are presented for aromatic and heterocyclic ring molecules resolved as a function of incident positron energy using a trap-based positron beam. Comparisons with the vibrational mode spectra yield positron-molecule binding energies. Good to excellent agreement is found between the measured binding energies and the predictions of an \textit{ab initio} many-body theory that takes proper account of electron-positron correlations including virtual-positronium formation. The calculations elucidate the competition between permanent dipole moments and $\pi$ bonds in determining the spatial distribution of the bound-state positron density. The implications of these results and the role of multimode features in annihilation in these molecules, including Fermi resonances, are discussed.

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Cited by in corpus (2)

• Many-body theory predictions of positron binding energies in five-membered heterocycles involving N, O, S and NH substituents
• Coupled cluster theory for positron binding in anions and polyatomic molecules