Fig. 1. Spectrum and IPR for the 2 nm, methylamine-passivated Cd₉₁Se₉₁.

Top: Absorption spectrum in arbitrary units (red) and density of transitions (blue). Black sticks show individual excited states, whose oscillator strengths have been broadened to create the absorption spectrum. Note the high density of states with little or no oscillator strength (i.e. dark states). Bottom: Inverse participation ratio (IPR) for electrons (green) and holes (magenta) for each excitation. A larger IPR corresponds to a more delocalized wavefunction. Clearly the dark, low-energy states are associated with localized states, while the bright states are significantly delocalized. Inset: Enlarged plot of the IPR for the higher-energy part of the excitation spectrum, i.e. E_ex > 2.9 eV.