Multiply-charged magnetoexcitons in low-dimensional structures

The frequencies and intensities of absorption lines of a ''hole + N electrons'' complex in a magnetic field are found. The motion of all particles is assumed to be two-dimensional, and the electron and hole quantum wells are assumed to be spatially separated. It is shown how Kohn's theorem can be extended to the case of a system with a finite total mass. The energy of a N-electron complex in a quantum ring oscillates as a function of the magnetic flux with a period that depends on N and the ratio of the masses. (C) 1997 American Institute of Physics.