United-atom limits for molecular-orbital continua and the characteristics of broadening beyond the limit

In collisions of 0.2-3.0-MeV ${\mathrm{Na}}^{+}$ with thick targets of Ti through Zn, relatively flat molecular-orbital continua are observed that extend from the characteristic separated-atom lines to the united-atom $L$-shell limits. The broadening of these continua beyond their respective united-atom limits is essentially target independent and can, to a good approximation, be fitted with half-Gaussians characterized by widths proportional to $E^{\frac{1}{4}}$, where $E$ is the energy of the incident ion. Similar continua are observed for ${\mathrm{Na}}^{+}$-target combinations that have as their limit the united-atom $M$ shell.