QUASI-ATOMIC FINE-STRUCTURE AND SELECTION-RULES IN QUANTUM DOTS

We probe the electronic shell structure of quasiatomic systems, realiz ed in GaAs-AlGaAs quantum dots, by resonant Raman spectroscopy. We obs erve a series of discrete spin-density excitations, whose energies are very close to single-particle level spacings in a quantum dot. The co mbined information from experiments at different wave vectors in the l ateral direction and from investigations with applied magnetic fields reveals a distinct set of Raman allowed transitions (Delta n, Delta m) , where changes Delta n and Delta m are changes in radial and angular momentum quantum numbers, respectively.