Figure 2. Effect of treatment with cobaltocene on inter-band and intra-band absorption spectra of PbSe NCs.

(a) Absorption spectra of 7.9 nm diameter PbSe NCs as a function of cobaltocene concentration. (b) Fitting of the absorption spectrum of pristine PbSe NCs to the sum of the three Gaussian bands (dashed black line) that describe the 1^st (α₁, dash red line), 2^nd (α₂, dash green line), and 3^rd (α₃, dash blue line) inter-band transitions. (c) Normalized absorption intensity Δα_i/α_i (i = 1, 2, 3) in each transition (1^st: red squares; 2^nd: green circles, 3^rd: blue triangles) for treated PbSe NCs as a function of the concentration of cobaltocene. Inset: Correlation of Δα₁/α_o1 and Δα₂/α_o2. (d) Pristine (solid black line) and cobaltocene-treated (dash red line) PbSe NCs.