INELASTIC LIGHT-SCATTERING IN THE REGIMES OF THE INTEGER AND FRACTIONAL QUANTUM HALL-EFFECTS

Recent resonant inelastic light scattering experiments in the fraction al quantum Hall regime highlight the power of the method in studies of electron-electron interactions in semiconductors of reduced dimension s. We review here light scattering experiments that determine gap exci tations in the regimes of the integer and fractional quantum Hall effe cts. At integer values of the Landau level filling factor we consider inter-Landau level excitations. In the fractional quantum Hall regime we discuss the determination of long-wavelength gap excitations and sp in waves in the incompressible quantum fluid at filling factor 1/3.