Strong Field Ionization of Ne$^{n+}$(n$<$=3) for an Ultrafast, 400 nm Laser Field

Total ionization yields are reported for neon (Ne$^{+}$ to Ne$^{3+}$ at intensities from 10$^{14}$ W/cm$^{2}$ to 10$^{17}$ W/cm$^{2}$ for a 400 nm laser field. Sequential ionization processes are modeled by tunneling ionization and shown to be accurate within a factor of two near saturation for Ne$^{+}$ and Ne$^{2+}$. Non-sequential multi-electron ionization is observed for the ionization yield of Ne$^{2+}$ and Ne$^{3+}$. The ratio of ion yields from 800 nm and 400 nm laser fields for neon charge states for Ne$^{2+ }$and Ne$^{3+}$ show non-sequential ionization for a 400 nm laser field is different when compared to that for an 800 nm laser field. A semi-classical, 3D relativistic rescattering model is compared to the data.