Morse potential energy curves for the lowest six states of the
rare gas positive ion dimers have been calculated
on the basis of experimental data. For the ground states, there
are sufficient measured data to define the
curves completely. For the excited states of all the positive ion
dimers except neon, there are sufficient
measured data to define the curves. To obtain these curves, new
assignments of vibrational progressions in
high-resolution photoelectron spectra previously published are made and
the vertical ionization potentials
obtained. The vertical ionization potentials are used to determine
the internuclear distances. The ground
state ionic and neutral radii for Ne to Xe are 63, 93, 105, and 123 pm
and 112, 152, 168, and 194 pm,
respectively. “Virtual” covalent radii for Ne to Xe are 69,
98, 111, and 126 pm. The curves are consistent
with the van der Waals radii of Ne to Xe, which are 154, 188, 200, and
218 pm. From the correlation
between the Morse parameters of the isoelectronic ions and the new data
for the rare gas positive ions, improved
Morse potential energy curves for both the halogen negative ion dimers
and the rare gas positive ion dimers
are obtained.