In our fitting procedure, it was necessary to place physically realistic bounds on the fit parameters, 𝑙 𝑀𝐹𝑃 and 𝜎 𝑛 𝑒 . An upper bound of 17 nm was placed on 𝑙 𝑀𝐹𝑃 because as the NC radius is decreased to become much smaller than the mean free path, surface scattering becomes the dominant damping mechanism and bulk damping becomes negligible. The fit becomes insensitive to the value of 𝑙 𝑀𝐹𝑃 , which tends to increase indefinitely if not constrained; constraining 𝑙 𝑀𝐹𝑃 to a maximum 17 nm circumvents this issue. The lower bound placed on the 𝜎 𝑛 𝑒 parameter is attributed to the minimum standard deviation in the number of dopant atoms incorporated into a single NC. This value is approximated by Poissonian statistics to follow the relationship: 𝜎 𝑁 𝑑 ≈ √ 𝜇 𝑁 𝑑 . After quantifying the dopant concentration in each sample by ICP-AES, we set the lower boundary of 𝜎 𝑁 𝑑 to √ 𝜇 𝑁 𝑑