MICRO-RAMAN SPECTROSCOPY OF BI2SR2CACU2O8+DELTA INTERCALATED WITH NICKEL PHTHALOCYANINE BENZENE

Micro-Raman measurements on pure Bi2Sr2CaCu2O8+delta (host) intercalat ed with conjugated ring-shaped molecules (guest) like nickel phthalocy anine (NiPc) and benzene have been carried out. Drastic changes due to intercalation have been observed in the peak frequencies, intensities and band widths of several vibrational modes of both the guest and th e host species. The anomalous variations in the peak frequencies and i ntensities of C = N aza group stretching and C-C pyrrole ring stretchi ng vibrations of the NiPc molecule as well as the vibrational modes of oxygen in the Cu-O planes of the host material reveal the possibility of charge transfer processes in the intercalated compounds from the g uest to the host species. The large increase in the bandwidths of many vibrational modes has been related to local distortions and to the in homogeneous distribution of guest species in the intercalated samples. The contention of charge transfer due to intercalation is also substa ntiated from STM/STS studies. The suppression of the superconductivity due to intercalation has been explained in terms of the charge transf er mechanism.