Now let's look at some experimental data for gold nanoparticles, from Stephan Link and Mostafa A. El-Sayed. "Size and temperature dependence of the plasmon absorption of colloidal gold nanoparticles." The Journal of Physical Chemistry B 103(21), 4212-4217 (1999). The plot below, from Figure 2, shows UV-vis absorption data for gold nanoparticles of different sizes. What common features do you see between the model data (resonance curve on the preceding page) and the experimental data? What are some significant differences? How does the resonant frequency change as the particle size decreases? According to the authors, what determines the scattering rate =1/ ? Why does it depend on the size of the particles? Does this model explain the size-dependent features in the plot? Why or why not? Based on the resonant wavelengths for particles of different sizes, what do you expect each solution of nanoparticles to look like? I.e., what color will it be when illuminated with white light? (We will find out on Thursday!)