High Energy Spin and Charge Excitation in La sub 2 CuO sub 4.

Inelastic light scattering studies of La sub 2 CuO sub 4, both pure and doped with lead, over the energy range 0-1 eV have revealed the presence of high frequency A sub (1g) scattering components, in the spectral region 3500-6000 cm sup (-1), while also providing the complete lineshape for the previously reported spin-pair mode of B sub (1g) symmetry. Two main bands, broad and overlapping are observed in this region, with maxima near 3500 and 5200 cm sup (-1). The various spectral features show different resonance behavior. We suggest that a model based upon coupled spin and charge excitations will be required to describe these spectra.