Resonant Raman Scattering by Elementary Electronic Excitations in Semiconductor Structures

We explain quantitatively why resonant Raman scattering spectroscopy, an extensively used experimental tool in studying elementary electronic excitations in doped low-dimensional semiconductor nanostructures, always produces an observable peak at the so-called ``single particle'' excitation although the standard theory predicts that there should be no such single particle peak in the Raman spectra. We have thus resolved an experimental puzzle which dates back more than 25 years.