  Scanning ion microscopy applications of novel focused ion beam (FIB) systems
based on ultracold rubidium (Rb) and cesium (Cs) atoms were investigated via
ion-induced electron and ion yields. Results measured on the Rb$^+$ and Cs$^+$
FIB systems were compared with results from commercially available gallium
(Ga$^+$) systems to verify the merits of applying Rb$^+$ and Cs$^+$ for
imaging. The comparison shows that Rb$^+$ and Cs$^+$ have higher secondary
electron (SE) yields on a variety of pure element targets than Ga$^+$, which
implies a higher signal-to-noise ratio can be achieved for the same dose in SE
imaging using Rb$^+$/Cs$^+$ than Ga$^+$. In addition, analysis of the
ion-induced ion signals reveals that secondary ions dominate Cs$^+$ induced ion
signals while the Rb$^+$/Ga$^+$ induced signals contain more backscattered
ions.
