Metallic and insulating phases of ${\mathrm{Li}}_{\mathit{x}}$${\mathrm{C}}_{60}$, ${\mathrm{Na}}_{\mathit{x}}$${\mathrm{C}}_{60}$, and ${\mathrm{Rb}}_{\mathit{x}}$${\mathrm{C}}_{60}$

Photoemission studies of Li and Na fullerides show a band of alkali-metal-induced states that is fully below the Fermi level for a stoichiometry of ${\mathit{A}}_2$${\mathrm{C}}_{60}$ and inverse photoemission results show a splitting of the unoccupied bands. Equivalent results for the Rb fullerides show the formation of only a metallic phase, ${\mathrm{Rb}}_3$${\mathrm{C}}_{60}$. For all three fullerides, doping to saturation produces nonmetallic ${\mathit{A}}_6$${\mathrm{C}}_{60}$ phases.