Laser ablation of YBa_{2}Cu_{3}O_{7-δ} as probed by laser-induced fluorescence spectroscopy

Ground-state populations of cationic and neutral Y, Ba, Cu, and neutral YO, BaO, and CuO are monitored by laser-induced fluorescence during laser ablation of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$. 193-nm photons completely dissociate CuO allowing the observation of a subsequent reaction of the Cu atom with ${\mathrm{O}}_2$ to form CuO. As a function of ${\mathrm{O}}_2$ pressure, the CuO signal increases to a maximum at approximately 120 mTorr of ${\mathrm{O}}_2$, presumably minimizing δ, and then falls to negligible levels by 400 mTorr. Ablation at 248 and 351 nm dissociates a smaller fraction of the CuO, i.e., nascent CuO is observed in the absence of ${\mathrm{O}}_2$.