One-dimensional model of a negative ion and its interaction with laser fields

We describe a two-electron ‘‘atom’’ in one space dimension. This one-dimensional system is treated fully quantum mechanically and with full electron correlation. Its bare eigenstates and eigenenergies are determined numerically by solving Schrödinger’s equation on a spatial grid. When the electron-electron interaction (of soft-core long-range Coulombic form) is taken equal in strength and opposite in sign to the electron-proton interactions, this atom is found to have only one bound state, and is similar in other ways to a negative ion. We give a Z-correlation diagram, showing the relation of the system’s energy spectrum to those of its isoelectronic partners, which are one-dimensional analogs of He, ${\mathrm{Li}}^{+}$, etc. We also calculate a large number of fully correlated two-electron time-dependent wave functions for the system under excitation by a laser field, and exhibit a number of results, including one-photon and multiphoton photodetachment rates, ac Stark shifted threshold closings, photoelectron spectra, and above-threshold detachment spectra, single-electron and double-electron ionization probabilities, and light-scattering spectra.