  The negatively charged quasi-two-dimensional exciton ($X^-$) is studied
numerically in the presence of a uniform B-field and various in-plane
confinements. The corresponding photoluminescence (PL) spectra, including
shakeup processes, are calculated. These calculations provide a quantitative
explanation of recent experimental PL spectra. The photoluminescence signatures
of charged excitons in quantum dots are also examined. Electron-hole pair
distriution functions are calculated which show the structure of the charged
exciton states (both ground and excited states). Increasing excitation reflects
a competition between two effects: partial ionization of either one or two
electrons.
