Nanoparticles created by the laser ablation of YBCO are reported. The experimental procedure entailed pulsed laser deposition (PLD) of YBCO at a high background pressure of 5 Torr O2. The sizes of the nanoparticles range from 3 to 5 nm and are typical of the depositions made using laser energies of 50 mJ per pulse. Optical emission spectroscopy was used to characterize the PLD plume. Under nanoparticle deposition conditions, the ...