https://doi.org/10.1140/epjd/s10053-026-01156-5
Regular Article - Atoms, Molecules, Ions, and Clusters
The two-photon detachment of the positronium negative ion
Department of Physics, University of North Texas, 76203, Denton, TX, USA
a
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Received:
6
November
2025
Accepted:
25
March
2026
Published online:
20
May
2026
Abstract
We present our calculations of the two-photon detachment cross section of the positronium negative ion (Ps
), in both the length and velocity forms for energies below the Ps(
) threshold. We consider both the 
S and D final states. We employ the Rayleigh–Ritz method to determine the Ps binding energy and the corresponding S bound-state wave function. We use the complex Kohn variational method to obtain the S and D final-state wavefunctions, and we solve an inhomogeneous differential equation to obtain the P intermediate-state wave function. The S bound-state, P intermediate-state, and final-state wave functions contain Hylleraas functions. We investigate the applicability of the Wigner’s and a modified Wigner’s threshold laws to the one- and two-photon detachment cross sections of Ps near the ionization threshold.
© The Author(s) 2026
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