OXYGEN-ISOTOPE EFFECT ON THE HIGH-FREQUENCY RAMAN PHONONS IN BI2SR2CACU2O8+DELTA

Raman spectra have been obtained from single-crystal samples of Bi2Sr2 CaCu2O8+delta With varying degrees of oxygen-isotope exchange. A compa rison of the high-energy (greater than or equal to 400 cm(-1)) vibrati onal spectra obtained from an unexchanged sample, a partially exchange d sample and a fully exchanged crystal has been carried out to obtain an unambiguous assignment of the A(1g) modes at 465 and 630 cm(-1). Th e 465 mode is assigned to c-axis vibrations of O(3) atoms in the Bi-O layers and the 630 mode to the O(2) apical oxygen atoms in the Sr-O la yers.