Emission characteristics of the plasma plume generated during KrF laser ablation of a Cr2O3 target in vacuum

Time and space resolved optical emission spectroscopy has been used to investigate the characteristics of the plasma plume generated during the KrF laser ablation of Cr2O3 targets in vacuum. The nature of plasma species, their energies, their space and temporal distributions were established. We showed that the species with high excitation energies (O(II) ions, E ∼25–30 eV) dominate the emission at intermediate plasma stages of evolution and near the target, followed by Cr(II) (E ∼3–16 eV), O(I) (E 10–16 eV) and Cr(I) (E ∼3–6 eV), which appear during plasma cooling. Peculiarly, the O(I) species gives lines in the 600–800 nm spectral range. Optical time-of-flight (TOF) measurements showed velocities around 3.6×104 m/s for the ionic species and 1.3×104 m/s for the neutral species.