Local Optical Spectroscopy in Quantum Confined Systems: A Theoretical   Description
  A theoretical description of local absorption is proposed in order to investigate spectral variations on a length scale comparable with the extension of the relevant quantum states. A general formulation is derived within the density-matrix formalism including Coulomb correlation, and applied to the prototypical case of coupled quantum wires. The results show that excitonic effects may have a crucial impact on the local absorption with implications for the spatial resolution and the interpretation of near-field optical spectra. 
O. Mauritz, G. Goldoni, F. Rossi, E. Molinari (INFM and Dipartimento   di Fisica, Univ. of Modena, Italy)