INELASTIC LIGHT-SCATTERING BY SPIN-DENSITY, CHARGE-DENSITY, AND SINGLE-PARTICLE EXCITATIONS IN GAAS QUANTUM WIRES

We report the observations of inelastic light scattering by the elemen tary excitations of the one-dimensional electron gas. The quantum wire s are fabricated from a modulation-doped single GaAs/AlxGa1-xAs quantu m well by electron-beam lithography and shallow electron-cyclotron-res onance reactive-ion etching. In spectra of intersubband excitations we observe a clear separation of spin-density and charge-density collect ive modes. The splitting associated with the lateral potential of the wires is also seen in transitions to states of the first excited level of the parent quantum well. Determinations of electron-electron inter actions in intersubband excitations of the one-dimensional electron ga s show large corrections due to the exchange terms (or vertex correcti ons) that represent the excitonic binding of the particle-hole pairs.