[Retracted] Influence of L-Tryptophan on Growth and Optical Properties of PbS Nanocrystalline Thin Films

Figure 15

Quantized energy levels of PbS-PbS-T nanocrystals. The excitonic levels located at ~1.4 eV, ~1.8 eV, and ~2.1 eV are due to higher energy transitions from ¹D_h → ¹D_e and ²S_h → ²S_e states.