Interband collective electronic excitations in resonant Raman scattering of two-subband quantum wires

Using the bosonization technique, a theory for the collective excitations o f the interacting electrons in quantum wires with two subbands occupied is developed. The dispersion relations for the intersubband charge and spin de nsity excitations are determined. The results are used to interpret the fea tures observed in recent measurements of the Raman spectra of AlGaAs/GaAs q uantum wires, particularly for photos energies near band gap resonance. It is shown that peaks previously identified as "single particle excitations" are signatures of higher order collective spin density excitations. Predict ions about the observability of the interband modes are made.