Laser ablation of YBCO: utilizing /sup 18/O to investigate the incorporation of oxygen into the laser plume

/sup 18/O has been used as a tracer to measure the transfer of oxygen from the chamber atmosphere into the laser induced plume. The amount of oxygen incorporated into the plume was found by laser ablating from a polycrystalline YBCO target onto a room temperature carbon substrate in an atmosphere of 50% /sup 16/O and 50% /sup 18/O. A series of such samples was prepared using deposition pressures ranging from 0.5 to 260 mTorr. The film stoichiometry, including, most importantly, the atomic fraction of /sup 18/O, for each sample was determined using Rutherford backscattering. The results show that the incorporation of /sup 18/O from the deposition atmosphere increases with increasing deposition pressure (50% /sup 16/O and 50% /sup 18/O) up to approximately 25 mTorr and then, unexpectedly, decreases for higher pressures.<>